Do not accept invitations to a room with more than 1 other user

[bolinocroustibat]

First, make sure that the bot does not accept invitations when it is a room with more than 1 other user/people.

...and later on, if Albert bot is invited to a room with more than 1 other user, ensure that he only responds when Albert bot is tagged

[nrolin]

First, make sure that the bot does not accept invitations when it is a room with more than 1 other user/people.

I'm not sure this is easy to do, private message is handled the same way as a room (you can even invite more people to a private conversation).

In my code I used the number of user because it's the only thing I found reliable, but there should be an other way (tchap client manages to sort it out). It would be possibly easier to join the room, then decide to immediately quit if it is not a private conversation.

ensure that he only responds when Albert bot is tagged

it should be fairly easy with https://code.peren.fr/open-source/tchapbot/-/merge_requests/2

[bolinocroustibat]

Ongoing PR: #43