Shift things to be more correct

Conflicts:
	third-party/CMakeLists.txt
Only define LUA_BUILD_AS_DLL on Win32.
Add define LUA_DL_USE_RTLD_GLOBAL to fix osgLua
More "no need to define LUA_BUILD_AS_DLL when not Windows"
Adjust/extend search path for Lua.
Add SearchPath simple class
Cleanup
AddToLuaPath
Clean up and fix
Remove unused methods
add method to LuaPath to get the lua directory.
Replace usage of the luapath object to do the dirty work of updating the package path
Remove dead code we just replaced.
Clean up and re-organize a bit.
Add extend as a member of the search path base.
Use that member function to keep it tidy and expressive
Remove some old duplicated code
Factor out duplicated code.
Put in some error checking.
Fix/simplify root dir paths