add a device message to ask for donations

[r10s]

if the app is in reasonable use (eg. for some weeks, with some amount of messages and chats created), we want to add a device message that ask for donations.

the text of the device message could be eg.

❤️ Seems you're using Delta Chat!

Please consider donating to help that Delta Chat stays free for everyone.

While Delta Chat is free to use and open source, development costs money.
Help keeping us to keep Delta Chat independent and make it even more awesome.

https://delta.chat/donate

once this is merged, we consider to add later similar messages for "ask for review" and "please set an avatar"

[iequidoo]

I suggest to keep the logic simple and, say, after two weeks, if there are >=10 encrypted outgoing messages (they should be encrypted because unencrypted ones may be from user's another MUA), add the device message. The question is how often to re-add it though, i'd suggest every time the number of messages doubles, but not more than once every two weeks. The number of chats doesn't necessarily matter, even "Saved Messages" can be useful enough.

EDIT: "Development costs time, developers need money" looks better to me, otherwise one could think that money is the purpose of the project which isn't true.

EDIT: I think that the reason should be explained shortly, why we haven't asked for donations before and do now. W/o reasoning it looks as a degradation in the project while with it the request could motivate people to help.

[adbenitez]

❤️ Seems you're using Delta Chat!

this is a bit silly, "❤️ Seems you're enjoying Delta Chat!" might fit better