Revert Pa3PyX support for cross-map demos

git-svn-id: svn://svn.code.sf.net/p/quakespasm/code/trunk/quakespasm@975 af15c1b1-3010-417e-b628-4374ebc0bcbd
Apply Baker's fix for cross-map demo playback (http://forums.inside3d.com/viewtopic.php?f=3&t=2397).

With that alone, the console would come down and slide up when the map changes in a demo.
I added a SCR_BeginLoadingPlaque() call in CL_ParseServerInfo, only done during demo playback, which shows the loading plaque and prevents the console from appearing and sliding up.

git-svn-id: svn://svn.code.sf.net/p/quakespasm/code/trunk/quakespasm@976 af15c1b1-3010-417e-b628-4374ebc0bcbd