- Use a TArray for backing up cvars overwritten by a demo.

git-svn-id: http://mancubus.net/svn/hosted/zdoom/zdoom/trunk@4184 a95907f1-e10c-0410-b46f-9e587ccb1026
- Added C_GetMassCVarString(), which C_WriteCVars() is now a wrapper around. (And the latter 
  should probably be factored away eventually.)

git-svn-id: http://mancubus.net/svn/hosted/zdoom/zdoom/trunk@4185 a95907f1-e10c-0410-b46f-9e587ccb1026