Add command with logic to change user's display name

[Nephyx]

This PR adds a new user command /display-name [NEW_DISPLAY_NAME] together with API call implementation which modifies user's display name in the database and immediately starts using it in the client.

A new display name can be composed of multiple words.

Related to necessary backend changes in Haider8/tmessage-api#3 and closes #39.

[pep8speaks]

Hello @Nephyx! Thanks for updating this PR.

• In the file tmessage/cli.py:

Line 63:13: E128 continuation line under-indented for visual indent

Comment last updated at 2019-10-12 21:36:19 UTC

[Haider8]

Any update on this pull request @Nephyx?

[Nephyx]

Any update on this pull request @Nephyx?

Hi, I am almost done with implementing the route protection and expect to have it done in one or two days (based on my availability due to work and other duties).