Updated images and fixed some code.

Updated necklace images so the rendering is now correct (shows back part
when NOT equipped now), added bracelet image, made usage bars on items
only show if the max durability is over 1 (one use items use 1), changed
inventory BG to look nicer, fixed durability on bone weapon and renamed
it to bone club, added "SHARP" and "BLUNT" to damage indicator in
inventory, made items declare their cooldown and changed how the credits
work.
Varied changes.

Fixed jeans/jumper/scarf images to have the correct sprite used when
(not) equipped, made game not resizable, added a mana exercise necklace
and mana experience value, added mana levelling when sufficient mana
experience is gained, added breaking message text to some items and made
the necklace of strangulation not hurt dead people.