- Moved bot related variables from player_t into a new FBot class.
- Renamed FBot to DBot and made it inherit from DThinker.
- Fixed: Bots added by players other than the net arbitrator did not have their skill set.
- Made DBot inherit from DObject.
Fixed Unknown CMake command "CHECK_LIBRARY_EXISTS" error on Unix targets

Previously it worked somehow but not with CMake 3.0.2
Fix handshakes between GCC and MSVC

u_long has two different sizes between Linux GCC and MSVC
Stopped netgames from starting up if player count wont fit
Change u_short as well.
Merge branch 'DBot' of https://github.com/ChillyDoom/zdoom
Merge branch 'fix_cmake_unix' of https://github.com/alexey-lysiuk/gzdoom
Merge branch 'master' of https://github.com/j-palomo/zdoom
Merge branch 'handshake-hotpatch' of https://github.com/Edward850/zdoom
- Removed p_leader.
- Fixed: Only setting controllers should be able to remove bots.
- Fixed: New DBot instances were missing write barriers.
- fixed: The sorting of 3D floors was incomplete and missed cases where translucent volumes overlapped non-translucent ones only at their top. It also didn't account for one translucent volume being intersected by more than solid one.
- added pickup sprite and editor number for Heretic's gold wand.
Added Inventory.AlwaysRespawn flag.