Separate action definition from actor action ownership

[andriusch]

Depends on #16

• Separates action definition from action action ownership. This means that definitions can be reused between actors and perhaps even moved to compendium at some point.
• Introduce collection classes for skill actions & skill action ownerships.
• Moved fromEvent function to skill action ownerships collection.

[andriusch]

Never mind this is bad idea, it goes against how foundry works where items in actor and in compedium use the same class. Not to mention some of this reimplements functions that already exist in foundry.