-Added Host_AbortCurrentFrame to hide the longjump and make it usable by

-Added Host_AbortCurrentFrame to hide the longjump and make it usable by
 the VM error functions.
-Moved the static variables of Host_Error into the function body.
-Changed the definition of error_cmd to be called instead of Host_Error,
 so the VM control code is in full control of the error processing.
-Added MP_Error to the menu, so a menu crash wont shutdown the server anymore.
-Fixed an annying bug caused by a typo, that crashes Nexuiz if you query for
 a string in the serverlist.
-PRVM_Crash resets the prog pointer now.
-PRVM_Begin use Con_Printf again (but PRVM_DEBUGPRSTACK has been disabled again).

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@5374 d7cf8633-e32d-0410-b094-e92efae38249