fix block array size calculation (debug message)
depend on zlib now

we'll use it for networking right now, but later on saving as well.
update INSTALL with zlib dep
dependency on boost iostreams for zlib data compression

make a tiny compression example in ::saveWorld..we'll expand upon this
to compress the packets we need to, and decompress them.
This is used mostly just for chunking.
make deserializepackettype take a pointer instead.
add compress/decompress functions