Allow to provide custom ICAL rrule

[FlorianSteenbuck]

I think it would be nice if you can define that a transaction to be executed at the last day of the month or even better the last day of the month - 2 days.

Also some banks do not work on special days like the weekend. Their for categories the days into working days, holidays and weekend days. And create a possibility to exclude and include these days in the best case with a possibility of create models for these.

If going to implement this you may questioning what to do with transaction that do not match the requirements. Here create a worst case action. I think it would be nice to let the user decide what to do then. Try it the next matching day or previous matching day. Important here is that I only mean the day that matching the day model not the plan (monthly, daily, weekly).

[mtotschnig]

The ICAL standard allows to define rules that express your requirements. I am not completely sure if the Android calendar system interprets these rules correctly, but I suppose it should. I already had the idea of allowing user to enter an ICAL rule manually. Providing an interface that goes beyond what you can do in Android's calendar app, is beyond the scope of what My Expenses can do.

[mtotschnig]

If you use a Calendar app allowing to configure more advanced plans, My Expenses will pick them up with the "Custom" option. For example CalenGoo allows to create plans for the last day of the month. So does https://github.com/SimpleMobileTools/Simple-Calendar

[mtotschnig]

Last day of month recurrence is now implemented (#786)