feat!: Rebuild text parsing. Remove (expr), add (sym)(str)(num)(nl)

Previously, (expr) had anonymous "str" "num" and "sym" nodes. Those are
now exposed. (sym) nodes retain the anonymous symbols, like (sym "*").
Additionally, (sym next: "str") indicates the symbol is before an immediate
(str), and (sym prev: "num") indicates the symbol is after a number.

Add (nl) in multiline text:
  - (paragraph)
  - (fndef (description))
  - (contents), in drawers, blocks, dynamic blocks, and latex_envs

Add "sub" and "final" fields to (stars)

.gitignore

@@ -5,3 +5,5 @@ build
 *.log
 /examples/*/
 /target/
+*.so
+*.o

README.md

@@ -5,22 +5,6 @@ usefully parse org files to be used in any library that uses tree-sitter
 parsers. It is not meant to implement emacs' orgmode parser exactly, which is
 inherently more dynamic than tree-sitter easily allows.
 
-## Overview
-
-This section is meant to be a quick reference, not a thorough description.
-Refer to the tests in `corpus` for examples.
-
-- Top level node: `(document)`
-- Document contains: `(directive)* (body)? (section)*`
-- Section contains: `(headline) (plan)? (property_drawer)? (body)?`
-- headline contains: `((stars), (item)?, (tag_list)?)`
-- body contains: `(element)+`
-- element contains: `(directive)* choose(paragraph, drawer, comment, footnote def, list, block, dynamic block, table)` or a bare `(directive)`
-- paragraph contains: `(expr)+`
-- expr contains: anonymous nodes for 'str', 'num', 'sym', and any ascii symbol that is not letters or numbers. (See top of grammar.js and queries for details)
-
-Like in many regex systems, `*/+` is read as "0/1 or more", and `?` is 0 or 1.
-
 ## Example
 
 ```org
@@ -48,20 +32,24 @@ Parses as:
 (document [0, 0] - [16, 0]
   body: (body [0, 0] - [4, 0]
     directive: (directive [0, 0] - [1, 0]
-      name: (expr [0, 2] - [0, 7])
+      name: (expr [0, 2] - [0, 7]
+        (str [0, 2] - [0, 7]))
       value: (value [0, 9] - [0, 16]
-        (expr [0, 9] - [0, 16])))
+        (str [0, 9] - [0, 16])))
     (paragraph [2, 0] - [3, 0]
-      (expr [2, 0] - [2, 4])
-      (expr [2, 5] - [2, 12])
-      (expr [2, 13] - [2, 16])
-      (expr [2, 17] - [2, 22])))
+      (str [2, 0] - [2, 4])
+      (sym [2, 5] - [2, 6])
+      (str [2, 6] - [2, 12])
+      (str [2, 13] - [2, 15])
+      (sym [2, 15] - [2, 16])
+      (str [2, 17] - [2, 22])
+      (nl [2, 22] - [3, 0])))
   subsection: (section [4, 0] - [16, 0]
     headline: (headline [4, 0] - [5, 0]
       stars: (stars [4, 0] - [4, 1])
       item: (item [4, 2] - [4, 12]
-        (expr [4, 2] - [4, 6])
-        (expr [4, 7] - [4, 12])))
+        (str [4, 2] - [4, 6])
+        (str [4, 7] - [4, 12])))
     plan: (plan [5, 0] - [6, 0]
       (entry [5, 0] - [5, 16]
         timestamp: (timestamp [5, 0] - [5, 16]
@@ -72,50 +60,55 @@ Parses as:
         (listitem [7, 2] - [8, 0]
           bullet: (bullet [7, 2] - [7, 3])
           contents: (paragraph [7, 4] - [8, 0]
-            (expr [7, 4] - [7, 8])
-            (expr [7, 9] - [7, 10])))
+            (str [7, 4] - [7, 8])
+            (str [7, 9] - [7, 10])
+            (nl [7, 10] - [8, 0])))
         (listitem [8, 2] - [11, 0]
           bullet: (bullet [8, 2] - [8, 3])
           checkbox: (checkbox [8, 4] - [8, 7]
-            status: (expr [8, 5] - [8, 6]))
+            status: (sym [8, 5] - [8, 6]))
           contents: (paragraph [8, 8] - [9, 0]
-            (expr [8, 8] - [8, 12])
-            (expr [8, 13] - [8, 14]))
+            (str [8, 8] - [8, 12])
+            (str [8, 13] - [8, 14])
+            (nl [8, 14] - [9, 0]))
           contents: (list [9, 0] - [11, 0]
             (listitem [9, 4] - [10, 0]
               bullet: (bullet [9, 4] - [9, 5])
               checkbox: (checkbox [9, 6] - [9, 9])
               contents: (paragraph [9, 10] - [10, 0]
-                (expr [9, 10] - [9, 14])
-                (expr [9, 15] - [9, 16])))
+                (str [9, 10] - [9, 14])
+                (str [9, 15] - [9, 16])
+                (nl [9, 16] - [10, 0])))
             (listitem [10, 4] - [11, 0]
               bullet: (bullet [10, 4] - [10, 5])
               checkbox: (checkbox [10, 6] - [10, 9]
-                status: (expr [10, 7] - [10, 8]))
+                status: (str [10, 7] - [10, 8]))
               contents: (paragraph [10, 10] - [11, 0]
-                (expr [10, 10] - [10, 14])
-                (expr [10, 15] - [10, 16])))))
+                (str [10, 10] - [10, 14])
+                (str [10, 15] - [10, 16])
+                (nl [10, 16] - [11, 0])))))
         (listitem [11, 2] - [12, 0]
           bullet: (bullet [11, 2] - [11, 3])
           contents: (paragraph [11, 4] - [12, 0]
-            (expr [11, 4] - [11, 8])
-            (expr [11, 9] - [11, 10])))))
+            (str [11, 4] - [11, 8])
+            (str [11, 9] - [11, 10])
+            (nl [11, 10] - [12, 0])))))
     subsection: (section [13, 0] - [16, 0]
       headline: (headline [13, 0] - [14, 0]
         stars: (stars [13, 0] - [13, 2])
         item: (item [13, 3] - [13, 13]
-          (expr [13, 3] - [13, 13]))
+          (str [13, 3] - [13, 13]))
         tags: (tag_list [13, 14] - [13, 19]
-          tag: (tag [13, 15] - [13, 18])))
+          tag: (tag [13, 15] - [13, 18]
+            (str [13, 15] - [13, 18]))))
       body: (body [14, 0] - [16, 0]
         (paragraph [15, 0] - [16, 0]
-          (expr [15, 0] - [15, 4]))))))
+          (str [15, 0] - [15, 4])
+          (nl [15, 4] - [16, 0]))))))
 ```
 
 ## Install
 
-For manual install, use `make`.
-
 For neovim, using `nvim-treesitter/nvim-treesitter`, add to your configuration:
 
 ```lua