BattleAutoEnd: the saga continues.

possibly the most confounding bug in this feature so far.
invert the invisible button.
fix debriefing bug.
restore end turn button functionality

turns out the AI ends it's turn in a lot more places than i thought.
Removed awkward BattleUnit copy constructor, which fixes a memory leak
Merge branch 'memoryleaks' of https://github.com/louisdx/OpenXcom into memoryleaks
Fixed a memory leak in InfoboxState