Fix a couple of warnings and do some reformatting.
Also tracks current color and attributes for each status field
and only updates them if they're being changed instead of every
time the value changes. Not very thoroughly tested so far.
The only attribute being supported is inverse but tty-style
status supports the full set. Also, changed values are always
highlighted in inverse even if there is no highlight rule.
That should probably only apply when 'statushilites' is 0,
giving the old fancy status highlighting when regular hilites
are turned off.
a2a9cb7b4f