Addplayer 2021 7 15

Resolves G_AddPlayer crash and R_SkinUsable always returning true on multiplayer character select

added 6 commits

• 95359fef...33ae95bf - 5 commits from branch addplayer
• bac41161 - Merge branch 'addplayer' of https://git.do.srb2.org/STJr/SRB2.git into addplayer-2021-7-15

Compare with previous version

merged

mentioned in commit 1285ba9f