Fix linux battery status display color.
Remove defaultstring.cc via make clean target since it's generated.
Allow enable/disable of coretemp and acpitemp from the command line.
Continue collecting metrics while not visiable.

The decay and graph field meters display metric history so the metrics
need to be collected even if the display is not visiable.
Draw all decayed fields that change width or position & simplify decay init.

Prior to this fix, a decayed field was not drawn if it did not change
width, even if it changed position.