Typing Tutor

* Modified: Makefile
* Modified: core.js
* Modified: src/JSNative.c
Deleted: src/JSNative.js
Added: src/JSNative/JSNative.js
Added: src/JSNative/JSNativeType.c
Added: src/JSNative/JSNativeType.h
* Modified: src/JSTools.c
* Modified: src/JSTools.h