Editor fix

Fixed

• BlackboardPropertyReferenceDrawer paths are fixed.

Editable components

Changed

• Some methods became aggressively inlined for performance reasons.
• Some methods got a pure attribute.
• Components became editable.

First Release

Added

• Blackboard and other core functionality.
• Blackboard serialization.
• Unity components support.
• Unity editor support.
• Tests.
• BlackboardPropertyReferenceDrawer:
  custom editor for BlackboardPropertyReference as public static methods.