Remove StockMessage.action_by_contact()

[link2xt]

Use separate strings for "... by me" and "... by contact" to make them easier to translate.

Fixes #3429

[r10s]

maybe even remove the "by me" variant, so also say on the senders device "action by NAME".

we talked about that in some chat, cc @adbenitez - advantages are fewer strings, less code and less confusion, eg. when using multiple accounts "by me" is not always clear. also, things look the same on sending and receiving devices (sender seens what the message reads on reveiver's side) and also fewer possible bugs in translations :)

[link2xt]

I changed strings "... done by me" to "You did ...". Other messengers say "you" in this case too.

Chat looking the same on all devices may be a good idea, but then we better remove "Me" string too and display username near the message. Message bubbles will still be placed left/right depending on whether the message is sent by us.

[r10s]

the "you did ..." is nice, indeed. i am fine with that as well :)

[link2xt]

This is ready for review.

[r10s]

This is ready for review.

great! i have this on my todo-list :) i will also create a corresponding android-pr and push the new strings to transifex then.

[link2xt]

@r10s I updated PR according to your review and regenerated node constants.

[r10s]

great! i will create a corresponding android pr soon and re-check/merge this one then. thanks a lot for pushing this forward!

[r10s]

resolved the CHANGELOG merge conflict and rebased.

[link2xt]

@r10s Fixed