conexusmm 0.2.0 released

This is the first independent release of conexusmm after splitting it from the conexus library.

Numerous serial and TTY widgets have been added as well as a complete TTYWidget providing an interface that should be sufficient for configuring most serial/tty devices.

The IPv4 widgets have also been rewritten and restructured to provide support for both IPv4 and IPv6 endpoints that were introduced in the 0.2.0 release of conexus.

This release also introduces conexusmm-demo, an interactive widget demo based upon the Gtkmm widget demonstrator.