Try to sanitize the exec+pullin mess

- Old mess:
  * Execute autoexec files right away.
  * Execute -exec files right away.
  * Execute command line commands right away.
    - If, during any of the above, an unknown command or a set of an
      unknown variable is encountered, store it for later.
    - Pullin commands are directly executed and add to the list of files
      to load.
  * Do a little setup, including parsing CVARINFOs.
  * Retry saved commands in case CVARINFO added a cvar they refer to.
- New, less messy, mess:
  * Parse autoexec files into an array.
  * Parse -exec files.
  * Parse command line commands.
    - During all of the above, exec commands are also parsed into the
      array immediately rather than being saved for execution later.
    - Pullin commands are parsed into a different array. The pullin
      command doesn't actually do anything directly anymore.
  * Add all the pullin files to the list of files to load.
  * Do a little setup, including parsing CVARINFOs.
  * Execute every command that was parsed in the preceding steps.

src/c_cmds.cpp

@@ -450,11 +450,10 @@ CCMD (exec)
 
 	for (int i = 1; i < argv.argc(); ++i)
 	{
-		switch (C_ExecFile (argv[i], gamestate == GS_STARTUP))
+		if (!C_ExecFile(argv[i]))
 		{
-		case 1: Printf ("Could not open \"%s\"\n", argv[1]); break;
-		case 2: Printf ("Error parsing \"%s\"\n", argv[1]); break;
-		default: break;
+			Printf ("Could not exec \"%s\"\n", argv[i]);
+			break;
 		}
 	}
 }