Implement new app drawer/menu

[konradrenner]

I tried to update to the latest version of MaterialDrawer from Mike Penz because the version in use makes many problems. But with the latest version many things are broken, really ugly broken :-(

So the best way would be to implement our own drawer, so that another dependency is gone.

The implementation should be not too difficult, but will be some work and much more testing :-).

[konradrenner]

so this one has now top priority, with the new possibilty of selecting the account in note detail, new problems with this drawer are here. also on newer android versions (starting with 7.0) the app crashes if the account is switched more than 2 times because of a exception in the drawer implementation

[konradrenner]

will be fixed in 3.0.0