Minecraft Beta 1.7.3

Bug fixes, bug fixes and bug fixes.

- Corrected a block duplication bug when using pistons
 - Corrected a redstone torch duplication bug when using pistons
 - Corrected a client crash when placing a sign in front of the piston, powering the piston and then removing the block beneath the sign
 - Ice blocks are now pushed without causing water streams breaking everything
 - Booster rails are no longer being powered magically without a power source
 - Pistons connected to the end of a piston-transistor via redstone are now properly closed when the power goes out
 - Doors no longer create purple particles
 - Hacking clients can no longer edit texts of placed signs in multiplayer
 - Changed so that paintings pushed by pistons will pop off