A realm filter should match only after the start of a line, whitespace
or opening delimiters. But markdown was not configured to respect those
rules which was causing some weird rendering behavior. This commit fixes
the regex used for matching realm filters. On the backend we are using
regex with negative lookbehind to perform matches but since javascript
regex don't support lookbehind we are using a workaround on the frontend
using `contains_backend_only_syntax()` function which detects if a realm
filter can be rendered correctly by backend only and if so it stops the
message from getting echoed locally.
Fixes: #5154.
Unicode emojis when rendered should display canonical short name.
Similarly, the alt text should be of the format `:<short_name>:`.
For both of these we currently display the actual unicode symbol.
As some systems don't have the fonts necessary for displaying them
properly, they are rendered as empty square blocks. This commit also
ensures that the markup generated for emoji generated by canonical
name and by an unicode emoji is same.
Fixes: #5555.
A deactivated realm emoji should neither be accepted further as a
reaction nor its further occurences in a message be rendered as an
emoji. However, all the old occurences should continue to render
normally.
This commit removes all references to feature_flags.local_echo.
It's been a core feature for about four years, so I think we
can safely say the experiment was successful.:)
Harshit Bansal
Tim Abbott
digi0ps
Steve Howell