Implement in-app custom time formatting editor

[tuur29]

This probably won't get added any time soon, but ideas and proposals can be added in this ticket.

To avoid future PRs like this #79 (and the adding of the "Numbered" translation in the first place).

Proposal

The following settings should be made exportable (backups) and shareable, perhaps to more easily add officially to the app in the future.

Clock

Add 3 sets of customizations, each is a list with a custom amount of items, containing a min-max slider linked to a string value. For example:

• Hours: 24 items in list, min and max are same for 24 hours, each a different translation, like: 3="three"
• Minutes: 5 ranges, like: 5-15="quarter"
• Clock: add the ability to flip around clock based on minutes and add extra words inside clock, like: 5-35="[MINUTES] past [HOUR]" 55-5="[HOUR] o'clock"

Date

Toggle between a simple list with all 7 days of week, or a list of all days in month (perhaps min-max slider as above).