make pause button more informative and useful also for automatic pausing

[mafrieger]

feature request: make pause button more informative and useful also for automatic pausing mode

-> would be handy to see directly at the pause button some information also if "automatic pause" is active
e.g. making button active (blue) like it's when "manual pause" is active but showing an "a" for automatic as button overlay

-> with this in "automatic pause" one could also restart rendering by clicking the button again like it's possible in "manual pause"...

what do you think?