Improv UI - draw cards same way like units

Also changed names to abstract
Spells can target heroes

- Add propery 'aceptHero' to AllUnits-, Random-, Player-targeters
- Rework PlayerData, so that health is stored in unit
- Add FieldSituation property "ArrayList<Unit> heroes" for those units
- "playerUnits" in fieldSituation now private, new getters added
- Update tests