This commit is a refactoring of the redstone code, mainly the functions
handling the removal of invalid blocks from power supplier data
structures. Its aim is to improve performance and potentially reduce the
memory footprint of the data structures.
It works to reduce the amount of GetBlock()s triggered every tick.
Before, a GetBlock() was requested for every single item in the data
lists, as well as for every single redstone block in a chunk. Following
these changes, the AddBlock() event is utilised more effectively to only
update the lists when needed (a block is changed), as well as to insert
the block type (and update it when needed) alongside the coordinates
into the main redstone simulator chunkdata list.
In short, a single GetBlock() is now cached, with this cache being
updated when the simulator is awoken due to a block change.
At least, I *hope* that this is what it does :P
