Merged dev changes 9/7/2019

- Experimental RPC stuff for the future
- Fixed players running over allies with vehicles (kind of)
- Modified redirect filter infrastructure to support when there's no target filter (meaning it will just make sure the entity exists)
- Fixed SDK_EyeRefract
- Fixed env_beam SetStart/EndEntity
- New "OnStateChange" output on NPCs
- scripted_face removed (use generic facing VCDs instead)
- Fixed RPC
- Miscellaneous code cleanup

sp/src/game/client/cdll_client_int.cpp

@@ -219,6 +219,9 @@ IEngineReplay *g_pEngineReplay = NULL;
 IEngineClientReplay *g_pEngineClientReplay = NULL;
 IReplaySystem *g_pReplay = NULL;
 #endif
+#ifdef MAPBASE
+IVEngineServer	*serverengine = NULL;
+#endif
 
 IHaptics* haptics = NULL;// NVNT haptics system interface singleton
 
@@ -949,6 +952,15 @@ int CHLClient::Init( CreateInterfaceFn appSystemFactory, CreateInterfaceFn physi
 		return false;
 #endif
 
+#ifdef MAPBASE
+	// Implements the server engine interface on the client.
+	// I'm extremely confused as to how this is even possible, but Saul Rennison's worldlight did it.
+	// If it's really this possible, why wasn't it available before?
+	// Hopefully there's no SP-only magic going on here, because I want to use this for RPC.
+	if ( (serverengine = (IVEngineServer*)appSystemFactory(INTERFACEVERSION_VENGINESERVER, NULL )) == NULL )
+		return false;
+#endif
+
 	if (!g_pMatSystemSurface)
 		return false;