This refactors the code to add zlib compression. A class called
SegmentParser is added to handle segmenting of the TCP stream so that
compressed chunks can be correctly decompressed. The packet format is
really simple:

+--------+--------------+
| LEN: 4 | PAYLOAD: LEN |
+--------+--------------+

LEN is a four byte field describing how long the payload is.
PAYLOAD is LEN bytes of compressed data.

Compressors can be added via the compressor interface.