Remove generated parsers' dependency on the runtime library

Generated parsers no longer export a parser constructor function.
They now export an opaque Language object which can be set on
Documents directly. This way, the logic for constructing parsers
lives entirely in the runtime. The Languages are just structs which
have no load-time dependency on the runtime

src/runtime/stack.h

@@ -0,0 +1,34 @@
+#ifndef RUNTIME_STACK_H_
+#define RUNTIME_STACK_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "tree_sitter/parser.h"
+
+typedef struct {
+  size_t size;
+  struct {
+    TSTree *node;
+    TSStateId state;
+    int is_extra;
+  } *entries;
+} TSStack;
+
+TSStack ts_stack_make();
+void ts_stack_delete(TSStack *);
+TSTree *ts_stack_reduce(TSStack *stack, TSSymbol symbol,
+                        size_t immediate_child_count,
+                        const int *hidden_symbol_flags, int gather_extras);
+void ts_stack_shrink(TSStack *stack, size_t new_size);
+void ts_stack_push(TSStack *stack, TSStateId state, TSTree *node);
+TSStateId ts_stack_top_state(const TSStack *stack);
+TSTree *ts_stack_top_node(const TSStack *stack);
+size_t ts_stack_right_position(const TSStack *stack);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // RUNTIME_STACK_H_