Also returning tool's display damage and max damage value from robot.durability, because some mods do (IMHO) odd things with those.
Made assembler a component so it can be queried for its status and assembly can be started automatically.
Cleaned up textures folder a little.
Changed how slot types are referred to internally in preparation of the Slot enum being removed in 1.4.
Implemented component bus item, which replaces the additional CPUs in servers (in existing servers, multiple CPUs will remain functional for now, they just can't be inserted any more, only component buses can). This is in preparation for #393, to allow make a computer's architecture be controlled via the CPU installed in it.
Made creative tier case only changeable when in creative mode, closes #476.
Made robots respect inventory.isUsableByPlayer.