Premake and HLSLParserListener.cpp update for lua 5.1.5

Replaced lua files with version 5.1.5
lua-5.2.0 added back
added lua51 option to premake script
fixed exclusion of second lua fileset
added lua_len fallback for LUA_VERSION_NUM < 502
Merge branch 'lua_5.1'

Conflicts:
	premake4.lua