Fixed heater sprites

Heaters no longer look like freezers, and their first letter is capitalized. I changed some parts about freezers too that should make them appear when editting the map, altough this will probably only work after they're removed and added again on the map.
![2013-07-04 14_05_16-beard relay upsilon](https://f.cloud.github.com/assets/3975713/749280/9ac2a222-e4a6-11e2-906f-5b362d762847.png)