Breaks configfiles! Major refactoring of i3status, see below

Breaks configfiles! Major refactoring of i3status, see below

We finally switched to libconfuse for a configuration file format
which does not require much work for the programmer nor for the user.
Plus, it avoids the Not-Invented-Here syndrome of yet another config
file format.

Furthermore, as a consequence of providing format strings for every
"module" (ipv6, wireless, …), we directly print the output and thus
we needed to drop support for wmii. This allowed us to get rid of
quite some complexity.

Documentation about the new configuration file and options will
follow. This commit is the beginning of what will be i3status v2.0.