Update to the newest lua_yajl.c.
Merge pull request #25 from ahmedcharles/lua_yajl

Update to the newest lua_yajl.c.
Sort the lists of files in src.pro.
Require Qt5.
Fix flags so that they work for mac and non-mac.
Use the suffix -dev for development builds.

Users can change this locally if they wish.
Cleanup and explain TARGET difference for Mac.