Version 0.3 - UNIX sockets and CMake

Version 0.3 brings several new features:

• Socket class hierarcy now splits out for streaming and datagram sockets.
• Support for UNIX-domain sockets.
• New modern CMake build system.
• GNU Make system marked for deprecation.

Version 0.2 - IPv4

Initial working version for IPv4.
API using boolean return values for pass/fail functions instead of syscall-style integers.