Other things with direction (torches, ladders, stairs, etc) will be
handled in a similar fashion. Note: minetracks on slopes are still
not rendered correctly
The following textures now no longer render as blocks:
* Flowers
* Mushrooms
* Saplings
* Reeds
* Torches
Note that torches attached to wall are still rendered incorrectly
The spawn point is automatically added to the gmap as a marker.
Adding other markers (signs, mob spawners, etc) should be fairly
easy. Note: the math that converts from in-game block coordinates
to pixel coordinates is iffy. it requires a careful codereview
Andrew Chin