Simplified the way Chickens are handled in the hatchery
- Chickens can be picked up
- Chickens can be dropped on claimed tiles
- Chickens leave hatchery only when dropped outside
- Chickens can live 30 turns outside the hatchery. After that, they die
- Only creatures using the hatchery will consider eating a chicken in the hatchery
- A creature not using the hatchery will consider eating chickens outside the hatchery only. Any creature, even ennemy can eat a free chicken
fixes #216
Renamed RoomObject to RenderedMovableEntity.
- Renamed RoomObject to RenderedMovableEntity
- Adapted Room/Trap/Missiles to use the same logic for construction
- Added boulder trap
- Traps now deal damage when Missile hits only (if it hits)
fixes #233
fixes #231
fixes #197
Added m prefix to a class member variable name
Merge pull request #238 from hwoarangmy/development

Simplified the way Chickens are handled in the hatchery
Added several new stats in the creature config file.

Most of them are now used when leveling up.

Also, the actual creature movement speed depending on the terrain is used
instead of its definition base value.

I also added a path() proxy function when called for creature for simpification
purpose.

For now, only the Physical attack/defense are used when fighting.
What's left to add is handling the natural range of the creature and split
physical/magical attack/defense.

Part of #152

Stats added in file.
    DigRate/Level
    ClaimRate/Level
    GroundSpeed/Level
    WaterSpeed/Level
    LavaSpeed/Level
    PhysicalAttack
    PhysicalAtk/Level
    MagicalAttack
    MagicalAtk/Level
    PhysicalDefense
    PhysicalDef/Level
    MagicalDefense
    MagicalDef/Level
Fixed the boulder trap icon position

Fixes #242