LuaTable: add return values to help chain method calls
New pi_lua_multiple_push to push as many stuff as one wants
Add a pi_lua_generic_push function for LuaRef
Add Call and CallMethod methods to LuaTable
Add a CallMethod static method to LuaObject
Move around some pi_lua_generic* functions to minimize interdependencies
Add builtin support for return values to Lua{Object, Table}::CallMethod
Use LuaObject::CallMethod for all the missile handling.
Non-variadic-recursive pi_lua_multiple_push version for MSVC
Merge branch 'cpp_calls_lua'