Add support for TS terrain sprites and non-square cell sizes.

This separates the x and y scaling factors between world and screen coordinates.  The internal simulation uses square tiles, so this introduces a forced perspective - this is used in the TS mod to reduce north-south movement speed and distort the range circles into ellipses.

This also adds initial support (basic tile data only) for Tmp(TS).

![terrain](https://f.cloud.github.com/assets/167819/1818749/5eb7c4f2-7028-11e3-8cb4-e4a21c728d79.png)

**This may break the map editor -- this needs to be tested.**