add mac Xcode example project.
Merge branch 'master' of http://github.com/cloudwu/ejoy2d
use recommend settings.
move the lua folder.
Merge commit 'bc0a032f62754b1b55d673215890b50d0f2e1d06'
remove lua.
Merge commit 'b4edd89d7293aae6a18b9cc2f7fcc36b9f28d041'
Merge pull request #41 from Tsiannian/master

add mac xcode example project.