[MP] Add stub UI script cmd for LaunchSP.
[SP] Add stub UI script cmd for LaunchMP.
[MP] Tidied up some of the CMake files.

In the vanilla renderer CMake file, I've renamed the 'qcommon' group
to 'common', and in the bot lib project, moved all the files into the
correct groups.
[SP] Fix Linux builds
[SP] Fix the fix for Linux builds.

__STDC_LIMIT_MACROS must be defined in C99 versions of the stdint.h header in
order for SIZE_MAX to be defined.