libcommon|Cleanup|All Games: Calculating mobj movement friction
The code for calculating friction was half-commonized already, with the function in libcommon having the logic for Doom and Heretic. This commit makes the friction calculation fully common so that the Mobj_Friction() in libcommon suits all games.
libcommon|Cleanup|All Games: Calculating mobj movement friction
The code for calculating friction was half-commonized already, with
the function in libcommon having the logic for Doom and Heretic. This
commit makes the friction calculation fully common so that the
Mobj_Friction() in libcommon suits all games.
Removed redundant code from the game plugins.