Average data usage widget

Invalid date

---Note: if the widget stops responding, just restart the device or delete and then add the widget again.----

V 2.3
- Changed accumulate data checkbox to slider, to specify how many months it is accumulated (if was enabled it is now 1)

V 2.2
- Allow changing number of decimals data numbers show
- Allow showing data in GB instead of MB
- Make history screen react to tweaks too (keep bar at 100% tweak)