Temporarily disable autosave feature

Not ready for next point release.

Allow comments in DeHackEd [PARS] section

Better, simpler fix for rendering liquid ceilings

Miscellaneous tweaks

Minor optimization to low graphic detail mode

Use 33% translucency for smoke trails, bullet puffs

Keep z-position of Arch-vile's fire attack updated

See
http:https://www.doomworld.com/vb/doom-general/68383-what-is-the-archvile-flame-supposed-to-look-like/.

Restore default gammacorrectionlevel to 0.75

I changed my mind.

Don't show ite for keys in HUD...

...if not used as sprite for pickup, (as done for ammo sprites in commit
5166acc).

Minor optimizations