add a cvar for skipping demo cvars

.dem files have some cvars written to their
first tick in WriteDemoCvars

this is done for consistency with the player's
view for analysis, however in many cases
customers would like to just view a demo
without having it change their client's settings

for these purposes, we can skip all console commands
which were recorded on the initial tick of the demo
from being inserted into the command buffer

Author: mastercoms

src/engine/cl_demo.cpp

@@ -41,6 +41,7 @@
 #include "tier0/memdbgon.h"
 
 static ConVar demo_recordcommands( "demo_recordcommands", "1", FCVAR_CHEAT, "Record commands typed at console into .dem files." );
+static ConVar demo_readinitialcommands( "demo_readinitialcommands", "1", 0, "Apply commands from the initial tick of .dem files. These are typically demo cvars." );
 static ConVar demo_quitafterplayback( "demo_quitafterplayback", "0", 0, "Quits game after demo playback." );
 static ConVar demo_debug( "demo_debug", "0", 0, "Demo debug info." );
 static ConVar demo_interpolateview( "demo_interpolateview", "1", 0, "Do view interpolation during dem playback." );
@@ -1222,8 +1223,11 @@ netpacket_t *CDemoPlayer::ReadPacket( void )
 					Msg( "%d dem_consolecmd [%s]\n", tick, command );
 				}
 
-				Cbuf_AddText( command );
-				Cbuf_Execute();
+				if ( tick != 0 || demo_readinitialcommands.GetBool() )
+				{
+					Cbuf_AddText( command );
+					Cbuf_Execute();
+				}
 			}
 			break;
 		case dem_datatables: