Support highlighting mentions and watched keywords

[ulyssa]

When the user is mentioned in a message, it should be highlighted. It should also be possible to configure keywords that the user wants highlighted, on both a global and per-profile level. Notifications should all be viewable somewhere, in a way where the user can jump to them.

[ptman]

Intentional mentions are being specced. Better than highlighting username or displayname in many cases.

[craftyguy]

having an option to run an arbitrary program (like notify-send or something else) would be cool too!

[ptman]

matrix-org/matrix-spec-proposals#3952

[mokasin]

Would also be nice to have a list of mentions. In a busy room, I often loose the message, where I was mentioned.