add on-click; improve ascii_bar; ditch regex

Sorry for making this two pull requests.

In this change, I've:
 - Added an on-click function which uses notify-msg to create a notification to display the time remaining until full charge/discharge.
 - Implemented simple global variables for customization of ascii_bar mode
 - Swapped out regex operations for string & list operations, which slightly reduces overhead and improves legibility.

Thanks for your time,
Adam