Add abilities to items that show up in the abilities list

[kwiesmueller]

The idea is that items can have abilities directly connected to them.

Requirements

• An item can come with multiple abilities (like attacks, block) which describe the respective outcomes
• Abilities for item in the Self inventory show up in the abilities list
• Sub items (like Ammo) also add abilities
  • Maybe the main item can define an ability template and sub item abilities can build on that
  • Something like "Gun: Fire Shock Bullet" where the description allows to add the damages for both
  • But that might be too much/complicated for a start