Fix macOS client/server failing to start from terminal

The macOS client and server were completely unusable when run from a
terminal. They blocked forever in `[NSApp run];` which was called by
Sys_InitProtocolHandler(). `applicationDidFinishLaunching` was never
called to exit the NSApp run loop.

Use SDL's SDL_DROPFILE event to receive URLs to handle on macOS instead.
This also handles URLs while the game is running (connect to new server)
instead of nothing happening when clicking a link while the game is
running.

code/sys/sys_main.c

@@ -643,20 +643,6 @@ void Sys_ParseArgs( int argc, char **argv )
 }
 
 #ifdef PROTOCOL_HANDLER
-/*
-=================
-Sys_InitProtocolHandler
-
-See sys_osx.m for macOS implementation.
-=================
-*/
-#ifndef __APPLE__
-char *Sys_InitProtocolHandler( void )
-{
-	return NULL;
-}
-#endif
-
 /*
 =================
 Sys_ParseProtocolUri
@@ -716,9 +702,9 @@ char *Sys_ParseProtocolUri( const char *uri )
 			}
 		}
 
-		bufsize = strlen( "+connect " ) + i + 1;
+		bufsize = strlen( "connect " ) + i + 1;
 		out = malloc( bufsize );
-		strcpy( out, "+connect " );
+		strcpy( out, "connect " );
 		strncat( out, uri, i );
 		return out;
 	}
@@ -815,10 +801,6 @@ int main( int argc, char **argv )
 
 	Sys_PlatformInit( );
 
-#ifdef PROTOCOL_HANDLER
-	protocolCommand = Sys_InitProtocolHandler( );
-#endif
-
 	// Set the initial time base
 	Sys_Milliseconds( );
 
@@ -865,6 +847,7 @@ int main( int argc, char **argv )
 #ifdef PROTOCOL_HANDLER
 	if ( protocolCommand != NULL )
 	{
+		Q_strcat( commandLine, sizeof( commandLine ), "+" );
 		Q_strcat( commandLine, sizeof( commandLine ), protocolCommand );
 		free( protocolCommand );
 	}