some bikeshedding

[illwieckz]

some bikeshedding, it can wait for the next release because it's boring to (re)build a map

first commit caulks some out-of-sight faces, I'm sure some of them will not be automatically caulked by some q3map2 lagorithm.

second commit removes some weird shapes that are probably remains from deleted stuff

third commit removes two steps that are under the floor, probably some copy-paste issue

there is no urge to merge this, and it can be made the forward way using the way to not add extra merge noise github usually adds

[illwieckz]

I finally merged this before building the whole again. Github not detected the merge because I have slightly edited one commit.