Rename methods by replacing "opaque" with "external"

This is to reflect the new meaning of these methods since
b2ec9e5, when they were updated to
process all external types from the perspective of the current type, not
only opaque types.

shared/src/main/scala/io/kaitai/struct/ClassCompiler.scala

@@ -19,7 +19,7 @@ class ClassCompiler(
 
   override def compile: CompileLog.SpecSuccess = {
     lang.fileHeader(topClassName.head)
-    compileOpaqueClasses(topClass)
+    compileExternalClasses(topClass)
     compileClass(topClass)
     lang.fileFooter(topClassName.head)
 
@@ -29,9 +29,9 @@ class ClassCompiler(
     )
   }
 
-  def compileOpaqueClasses(topClass: ClassSpec) = {
-    TypeProcessor.getOpaqueClasses(topClass).foreach((classSpec) =>
-      lang.opaqueClassDeclaration(classSpec)
+  def compileExternalClasses(topClass: ClassSpec) = {
+    TypeProcessor.getExternalClasses(topClass).foreach((classSpec) =>
+      lang.externalClassDeclaration(classSpec)
     )
   }
 

shared/src/main/scala/io/kaitai/struct/NimClassCompiler.scala

@@ -21,7 +21,7 @@ class NimClassCompiler(
 
   override def compile: CompileLog.SpecSuccess = {
     lang.fileHeader(classNameFlattened(topClass))
-    compileOpaqueClasses(topClass)
+    compileExternalClasses(topClass)
 
     // if there are any enums at all maybe we can detect it and not generate this template
 //    nimlang.enumTemplate

shared/src/main/scala/io/kaitai/struct/TypeProcessor.scala

@@ -7,28 +7,28 @@ import io.kaitai.struct.format._
 import scala.collection.mutable
 
 object TypeProcessor {
-  def getOpaqueClasses(curClass: ClassSpec): Iterable[ClassSpec] = {
+  def getExternalClasses(curClass: ClassSpec): Iterable[ClassSpec] = {
     val res = mutable.Set[ClassSpec]()
     curClass.seq.map((attr) =>
-      res ++= getOpaqueDataTypes(attr.dataType, curClass)
+      res ++= getExternalDataTypes(attr.dataType, curClass)
     )
     curClass.instances.foreach { case (_, inst) =>
       inst match {
         case pis: ParseInstanceSpec =>
-          res ++= getOpaqueDataTypes(pis.dataType, curClass)
+          res ++= getExternalDataTypes(pis.dataType, curClass)
         case _ => None
       }
     }
 
     // Traverse all nested types recursively
     curClass.types.foreach { case (_, nestedType) =>
-      res ++= getOpaqueClasses(nestedType)
+      res ++= getExternalClasses(nestedType)
     }
 
     res
   }
 
-  def getOpaqueDataTypes(dataType: DataType, curClass: ClassSpec): Iterable[ClassSpec] = {
+  def getExternalDataTypes(dataType: DataType, curClass: ClassSpec): Iterable[ClassSpec] = {
     dataType match {
       case ut: UserType =>
         if (ut.isExternal(curClass)) {
@@ -38,10 +38,10 @@ object TypeProcessor {
         }
       case st: SwitchType =>
         st.cases.flatMap { case (_, ut) =>
-          getOpaqueDataTypes(ut, curClass)
+          getExternalDataTypes(ut, curClass)
         }
       case _ =>
-        // all other types are not opaque external user types
+        // all other types are not external user types
         List()
     }
   }

shared/src/main/scala/io/kaitai/struct/languages/CppCompiler.scala

@@ -108,7 +108,7 @@ class CppCompiler(
     }
   }
 
-  override def opaqueClassDeclaration(classSpec: ClassSpec): Unit = {
+  override def externalClassDeclaration(classSpec: ClassSpec): Unit = {
     classForwardDeclaration(classSpec.name)
     importListHdr.addLocal(outFileNameHeader(classSpec.name.head))
   }

shared/src/main/scala/io/kaitai/struct/languages/JavaScriptCompiler.scala

@@ -58,7 +58,7 @@ class JavaScriptCompiler(typeProvider: ClassTypeProvider, config: RuntimeConfig)
     out.puts("});")
   }
 
-  override def opaqueClassDeclaration(classSpec: ClassSpec): Unit = {
+  override def externalClassDeclaration(classSpec: ClassSpec): Unit = {
     val className = type2class(classSpec.name.head)
     importList.add(s"./$className")
   }

shared/src/main/scala/io/kaitai/struct/languages/LuaCompiler.scala

@@ -32,7 +32,7 @@ class LuaCompiler(typeProvider: ClassTypeProvider, config: RuntimeConfig)
   override def outImports(topClass: ClassSpec) =
     importList.toList.mkString("", "\n", "\n")
 
-  override def opaqueClassDeclaration(classSpec: ClassSpec): Unit =
+  override def externalClassDeclaration(classSpec: ClassSpec): Unit =
     importList.add("require(\"" + classSpec.name.head + "\")")
 
   override def fileHeader(topClassName: String): Unit = {

shared/src/main/scala/io/kaitai/struct/languages/NimCompiler.scala

@@ -54,7 +54,7 @@ class NimCompiler(typeProvider: ClassTypeProvider, config: RuntimeConfig)
     out.puts
   }
 
-  override def opaqueClassDeclaration(classSpec: ClassSpec): Unit =
+  override def externalClassDeclaration(classSpec: ClassSpec): Unit =
     importList.add(classSpec.name.head)
   override def innerEnums = false
   override val translator: NimTranslator = new NimTranslator(typeProvider, importList)

shared/src/main/scala/io/kaitai/struct/languages/PerlCompiler.scala

@@ -50,7 +50,7 @@ class PerlCompiler(typeProvider: ClassTypeProvider, config: RuntimeConfig)
     out.puts("1;")
   }
 
-  override def opaqueClassDeclaration(classSpec: ClassSpec): Unit =
+  override def externalClassDeclaration(classSpec: ClassSpec): Unit =
     importList.add(type2class(classSpec.name.head))
 
   override def classHeader(name: List[String]): Unit = {

shared/src/main/scala/io/kaitai/struct/languages/PythonCompiler.scala

@@ -77,7 +77,7 @@ class PythonCompiler(typeProvider: ClassTypeProvider, config: RuntimeConfig)
     out.puts
   }
 
-  override def opaqueClassDeclaration(classSpec: ClassSpec): Unit = {
+  override def externalClassDeclaration(classSpec: ClassSpec): Unit = {
     val name = classSpec.name.head
     importList.add(
       if (config.pythonPackage.nonEmpty) {

shared/src/main/scala/io/kaitai/struct/languages/RustCompiler.scala

@@ -54,7 +54,7 @@ class RustCompiler(typeProvider: ClassTypeProvider, config: RuntimeConfig)
     out.puts
   }
 
-  override def opaqueClassDeclaration(classSpec: ClassSpec): Unit = {
+  override def externalClassDeclaration(classSpec: ClassSpec): Unit = {
     val name = type2class(classSpec.name.last)
     val pkg = type2classAbs(classSpec.name)
 

shared/src/main/scala/io/kaitai/struct/languages/components/LanguageCompiler.scala

@@ -75,12 +75,12 @@ abstract class LanguageCompiler(
   def fileFooter(topClassName: String): Unit = {}
 
   /**
-    * Outputs declaration of "opaque class", i.e. class that will be referred to in this file, but
+    * Outputs declaration of "external class", i.e. class that will be referred to in this file, but
     * not declared here. Some languages require either a "forward declaration" in this case, or a
-    * statement to import that class, or something similar. Called once per each opaque class.
+    * statement to import that class, or something similar. Called once per each external class.
     * @param classSpec
     */
-  def opaqueClassDeclaration(classSpec: ClassSpec): Unit = {}
+  def externalClassDeclaration(classSpec: ClassSpec): Unit = {}
 
   def classDoc(name: List[String], doc: DocSpec): Unit = {}
   def classHeader(name: List[String]): Unit