erc: increase column width for nicks
erc: adapt fill column and center when window size changes
init: enable midnight to clean unused buffers
erc: add a cleanup function for closed erc buffers
init: disable fci-mode

The reason is that there is a bug in Emacs 24.3 that makes the cursor
jumps two lines instead of one and this is quite annoying. See:
 https://github.com/alpaker/Fill-Column-Indicator/issues/31