Quran 2.6.4

additional bugfixes.

as a result of the logging added yesterday for the notification issues, it seems as though the notification problem happens at random - as in we'll get many many working notifications, and then one will crash. as a means of trying to ameliorate this, this patch groups the notifications to avoid unnecessary notifications (i.e. if we are asked to notify an updated percentage which matches the last updated percentage, don't update the notification).

note that neither of the two experiments run in v2.6.3 (one for OnePlus kitkat devices where we'd replace the progress bar with progress subtext, and the other for all other kitkat devices where we'd disable indeterminate mode) seemed to have an effect on the crashes. hopefully grouping these to have less notifications will bring the rate of notification crashes down insha'Allah.