Add fps limiter for background window.
Background fps limit should not be 0 (possible div by 0).
Fix gcc compiler warnings from -Wall, including:

unused variables or methods (-Wunused)
uninitialized variables (-Wuninitialized)
signed/unsigned comparisons (-Wsign-compare)
order of initiliazers (-Wreorder)
just some palette depth stuff, nothing to see here
reduce copypasta
only look at SDL_Event.key for key-type events
make converted soldier zombies visible to begin with.
Merge pull request #883 from ajschult/keyUMR

only look at SDL_Event.key for key-type events
Merge pull request #882 from ajschult/warnings

Fix gcc compiler warnings from -Wall
Merge branch 'background_fps' of https://github.com/topaxi/OpenXcom

Conflicts:
	src/Engine/Options.inc.h
add item limit

configurable in craft rules, does not limit base defenses.
why you people want this is beyond me.
nope, don't like it, that's going off by default.
Some code related to MiniBaseView is refactored.
New Feature: Unlimited bases
Default: OFF
You can build any number of bases, even more than 8.
PsiTrainingState is now scrollable.
(if the player has more than 8 bases with PsiLabs)
Fixing the saving of the selected base.