Reorganize repo, add rust CLI and binding code,

lib/src/tree_cursor.h

@@ -0,0 +1,20 @@
+#ifndef RUNTIME_TREE_CURSOR_H_
+#define RUNTIME_TREE_CURSOR_H_
+
+#include "runtime/subtree.h"
+
+typedef struct {
+  const Subtree *subtree;
+  Length position;
+  uint32_t child_index;
+  uint32_t structural_child_index;
+} TreeCursorEntry;
+
+typedef struct {
+  const TSTree *tree;
+  Array(TreeCursorEntry) stack;
+} TreeCursor;
+
+void ts_tree_cursor_init(TreeCursor *, TSNode);
+
+#endif  // RUNTIME_TREE_CURSOR_H_