Add "grows" property for Cyphesis

Currently plants have ability to grow, given the changes in the metabolism code this should be moved into property too. I suggest making numerical property with "set_handler" that will account for check for changes in the mass of entity and increase the bbox and model accordingly. Possibly we should implement growin...

Add a "metabolizing" property for Cyphesis

Move the metabolizing code in Plant.cpp and Character.cpp into a property "metabolizing".

Add steppe nomad clothing and accessories for Ember

Create models and corresponding modeldefinitons for steppe nomad outfit. Namely: footwear, pants, leather jacket, bow, gorytos and sword/knife.

Implementing iron smelting process for Cyphesis

Implement iron smelting process which covers: mining an ore, smelting it in the bloomery and forging bloom(sponge iron) into bars.