Count milliseconds per SOL instead of in a global
Pass command handler as a parameter to SOL functions

This removes another piece of global state. This looks really, really
ugly at the moment, but does point the code in the right direction.
Move item renderer to the geom module
Process entity-based animation in SOL renderers
Merge pull request #71 from parasti/sol-move

Process entity motion in non-level SOL renderers