Add the ability to fire pellets
Fix bug - can't walk on your own pellets

Generalized code for transparency
Graphics for higher block levels
Tell clients when NPCs are deleted, too
Honor W/A/D as well as Up/Left/Right
Add ability for player to build a block where (s)he is
Allow player to create blocks with higher HP and different looks
1) Higher-level blocks are better at staying up 2) New command 'brake'
Block should stop (not just not-accelerate) when support requirements met
Add a rise-up maneuver

This complicated fiber-logic worked correctly on the first try.  I didn't expect that at all.  OK, there is a mild glitch on the client side; it thinks the player should move an extra pixel, and start to fall.  I'll sort that out later.  On the server side, though, this works just like I hoped.

Code is currently ugly and I'm sure it can be cleaned up.