Create an IndigoOptions type for the plugin (#590)

* Move existing build options into type, and refactor.

* Integrate the new IndigoOptions

* Improved IndigoOptions scaladoc

demos/pirate/build.sbt

@@ -1,4 +1,4 @@
-import indigoplugin.ElectronInstall
+import indigoplugin.IndigoOptions
 
 Global / onChangedBuildSource := ReloadOnSourceChanges
 
@@ -26,14 +26,12 @@ lazy val pirate =
       Test / scalaJSLinkerConfig ~= { _.withModuleKind(ModuleKind.CommonJSModule) }
     )
     .settings( // Indigo specific settings
-      showCursor            := true,
-      title                 := "The Cursed Pirate",
-      gameAssetsDirectory   := "assets",
-      windowStartWidth      := 1280,
-      windowStartHeight     := 720,
-      disableFrameRateLimit := false,
-      electronInstall       := ElectronInstall.Latest,
-      backgroundColor       := "black",
+      indigoOptions := 
+        IndigoOptions.defaults
+          .withTitle("The Cursed Pirate")
+          .withWindowStartWidth(1280)
+          .withWindowStartHeight(720)
+          .withBackgroundColor("black"),
       libraryDependencies ++= Seq(
         "io.indigoengine" %%% "indigo-json-circe" % IndigoVersion.getVersion, // Needed for Aseprite & Tiled support
         "io.indigoengine" %%% "indigo"            % IndigoVersion.getVersion, // Important! :-)

demos/snake/build.sc

@@ -8,20 +8,18 @@ import mill.scalajslib.api._
 import mill.scalalib.scalafmt._
 import coursier.maven.MavenRepository
 
-import $ivy.`io.indigoengine::mill-indigo:0.15.0-RC3`, millindigo._
+import $ivy.`io.indigoengine::mill-indigo:0.15.0-RC4`, millindigo._
 
 object snake extends ScalaJSModule with MillIndigo with ScalafmtModule {
   def scalaVersion   = "3.3.0"
   def scalaJSVersion = "1.13.1"
 
-  val gameAssetsDirectory: os.Path     = os.pwd / "assets"
-  val showCursor: Boolean              = true
-  val title: String                    = "Snake - Made with Indigo"
-  val windowStartWidth: Int            = 720
-  val windowStartHeight: Int           = 516
-  val disableFrameRateLimit: Boolean   = false
-  val electronInstall: ElectronInstall = ElectronInstall.Latest
-  val backgroundColor: String          = "black"
+  val indigoOptions: IndigoOptions =
+    IndigoOptions.defaults
+      .withTitle("Snake - Made with Indigo")
+      .withWindowStartWidth(720)
+      .withWindowStartHeight(516)
+      .withBackgroundColor("black")
 
   def buildGame() = T.command {
     T {