Change the way pinnable window are made visible

This ensure pinned window are not displayed in main menu, dialogue and
container mode.
Make the "lock window" button to change state visually
Make the "lock window" button appealing
Remove "PinToggle" event from layout file
NIF bullet loader fix for incorrect collision shapes (credit goes to Chris, he asked me to push this)
Merge remote-tracking branch 'scrawl/next' into next
Merge remote-tracking branch 'potatoesmaster/pinned' into next