Add lua 5.5 support

Author: halx99

include/sol/compatibility/compat-5.4.h

@@ -17,15 +17,15 @@ extern "C" {
 }
 #endif
 
-#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM == 504
+#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM >= 504
 
 #if !defined(LUA_ERRGCMM)
-/* So Lua 5.4 actually removes this, which breaks sol2...
+/* So Lua 5.4 or later actually removes this, which breaks sol2...
  man, this API is quite unstable...!
 */
 #  define LUA_ERRGCMM (LUA_ERRERR + 2)
 #endif /* LUA_ERRGCMM define */
 
-#endif // Lua 5.4 only
+#endif // Lua 5.4 or later
 
 #endif // NOT_KEPLER_PROJECT_COMPAT54_H_

include/sol/state.hpp

@@ -27,6 +27,12 @@
 #include <sol/state_view.hpp>
 #include <sol/thread.hpp>
 
+#if LUA_VERSION_NUM >= 505
+#  define sol_lua_newstate(f, ud) lua_newstate(f, ud, 0)
+#else
+#  define sol_lua_newstate(f, ud) lua_newstate(f, ud)
+#endif
+
 namespace sol {
 
 	class state : private std::unique_ptr<lua_State, detail::state_deleter>, public state_view {
@@ -39,7 +45,7 @@ namespace sol {
 		}
 
 		state(lua_CFunction panic, lua_Alloc alfunc, void* alpointer = nullptr)
-		: unique_base(lua_newstate(alfunc, alpointer)), state_view(unique_base::get()) {
+		: unique_base(sol_lua_newstate(alfunc, alpointer)), state_view(unique_base::get()) {
 			set_default_state(unique_base::get(), panic);
 		}