Finish Chapter 14

Implements code chunks, a couple of basic opcodes, constants, and
basic execution of those opcodes.

Signed-off-by: Daniel Henry <iamdanhenry@gmail.com>

src/main.c

@@ -0,0 +1,16 @@
+#include "chunk.h"
+#include "common.h"
+#include "debug.h"
+
+int main(int argc, const char *argv[]) {
+  Chunk chunk;
+  initChunk(&chunk);
+  int constant = addConstant(&chunk, 1.2);
+  writeChunk(&chunk, OP_CONSTANT, 123);
+  writeChunk(&chunk, constant, 123);
+  writeChunk(&chunk, OP_RETURN, 123);
+
+  disassembleChunk(&chunk, "test chunk");
+  freeChunk(&chunk);
+  return 0;
+}