model skin object to store and save customisable model elements
give each ship a skin
make the spinners take a skin
make SetLabel modify the ship skin
color->lua conversion method
scenegraph lua setup and model stubs
Merge branch 'lua-cleanup-2' into model-skin
skin ships in the shipyard
make ModelSkin RefCounted so that Lua can use it
randomise colour on new ships
Ship.skin attribute
get the skin through to the model spinner