Multi-monitor support

[zeorin]

I used guimeira/i3lock-fancy-multimonitor as inspiration (because I wasn't satisfied with it--couldn't change the text), and changed the lock script to support multiple monitors. Fixes #10.

Should also work for more than 2 monitors.

[AladW]

Should be split to several, overseeable commits. The general approach also needs improving if this is to be merged to the main branch, such as no keeping xrandr output as a big string and parsing it with bash_rematch and no extraneous use of eval either.

[michaelplews]

@zeorin I'm using this pull request for my day to day and it's been working great. I wanted to adjust the code to where the overlay can only be applied to one monitor, perhaps with a flag and option such as -m=0 for the primary display or -m=1 for the secondary display.

I was looking at your code to find where you iterate over the list of attached monitors but couldn't see it, could you point me in the right direction?

[AladW]

No response, closing.