Merge pull request #114 from clintbellanger/master

merge from master
visible_requires_status for menu powers
Adapt to coding style
Convert Power_Menu_Cell::visible_requires_[status,not] to lists
Merge pull request #121 from stefanbeller/779

Convert Power_Menu_Cell::visible_requires_[status,not] to lists
Merge pull request #779 from RyanDansie/power_menu_requires_status

Menu powers hidden depending on quest status