Fix incorrect absorb max calculations

Closes #500
Merge pull request #503 from dorkster/bugfixes

Fix incorrect absorb max calculations
Merge pull request #506 from hean01/master

Fix problematic string escaping and updated translations with a few missing strings.
Update the Norwegian Bokmål translation for the upcoming v0.18 release
Merge pull request #507 from hansjoachim/update-norwegian-translation

Update the Norwegian Bokmål translation for the upcoming v0.18 release
Removed Byte order mark (BOM) from languages.txt.

This caused a bug where selecting a language in the options menu would instead
give you the language above the one you selected. Presumably it failed to
parse the comment on the first line properly due to the BOM character, thus
believing it is a language code, thus pushing everyone else down one place.
AnimationSet: delete default animation on destruction.
MenuNPCActions: delete image in dtor
MenuInventory: Prevent invalid memory access
Refactor passive power activation

Closes #510

* effects are now removed when clearing item power lists
* effects are removed when the player doesn't meet the requirements for
the passive power that created them
Fix item passives only working once
Update engine.pl.po

Updated "fuzzy" translations
Fix for Ouroboros rings
Small fixes to german translation
Merge pull request #508 from hansjoachim/languages-BOM

Removed Byte order mark (BOM) from languages.txt.
Merge pull request #512 from dorkster/effects

Refactor passive power activation
Merge pull request #509 from stefanbeller/memleaks

Fix memleaks.
Merge pull request #518 from stefanbeller/de

Small fixes to german translation
Merge pull request #513 from Pawonashi/patch-4

Update engine.pl.po
Don't require restart to update keybind labels

Closes #514