Deal with prefer encryption correctly

joscha1
2020-02-21T10:02:59Z

* [ ] Read https://autocrypt.org/level1.html
* [ ] Discussion with Oliver
* [ ] by default, prefEnc should be true and only false if the owner of the address has set it to false
* [ ] depending on prefEnc the sendView should send it encrypted or not
* [ ] there should probably be some information to the user about that
* [ ] Can a user change the own prefEnc state? What is the default state?
* [ ] A user should be able to enforce encryption
* [ ] A user should be able to set a default encryption preference: Enforce encryption every time or following prefEnc...