Add weather to tmux statusline.

tmux.conf, tmux/weather.py
    -Add a segment containing information about the current weather to
    the `tmux` statusline.
Retab weather.py, add documentation.

tmux/weather.py
	-`weather.py` was accidentally saved with soft-tabs; perform a
	hard-retab.
	-Add docstring to module header and `get_weather()`.
Move statusline config from tmux.conf to new file.

tmux.conf, tmux/statusline.conf
	-Create `tmux/statusline.conf`, to contain all of the `tmux`
	statusline config that was originally kept in `tmux.conf`.
Minor mod to cpu_temperature.sh, music.sh.

tmux/cpu_temperature.sh
	-Remove "CPU:" from segment.

tmux/music.sh
	-`cmus-remote -Q` exit-code was erroneously assumed to remain in
	`$?` between its global-scope assignment and conditional check
	in `cmus_info()`. Change to a declaration of `cmus_info` at the
	global level, and assignment right before said conditional.
Merge branch 'feature/tmux_statusline_improve' into develop

tmux.conf, tmux/*
	-Add weather segment to the statusline; create standalone
	statusline config file, `tmux/statusline.conf`. Implement
	miscellaneous changes in the `tmux/*` scripts.