[SP] Disable g_delayedShutdown in debug builds by default now too.

Turns off the map bug detection feature as identified in issue #424 which existed in jasp, just not turned on by default since no debug ever public.
Migrated JK2 to JKA qcommon.
Replaced some JK2 header files with their JKA equivalents.
Replaced JK2 gameinfo with JKA equivalent.