Version 0.0.95 RC3

Yet another round before the final release. Changes on top of RC2:

• (ae4fe69) First and foremost - now that it's 2021 out there, Quaternion requires Qt 5.11 or newer. Qt 6 is not on the maps for 0.0.95.
• (#789) Reaction buttons no more render their captions as HTML - packagers are strongly advised to backport at least this fix to earlier 0.0.95 snapshots if you can't pull them to RC3.
• (#630, thanks to @rpallai) PageUp/PageDown should more reliably scroll to the respective edge now.
• (#758) Fix whitespaces being squashed in messages.
• (#781) Fix stray $ signs showing up around mentions and other markup.
• (#749) The message entry box is constrained by height now, showing a scrollbar if you type a too high message.
• (#780, thanks to @ddanilov) The room topic can be collapsed - click the right mouse button.
• (561ebdc) Quaternion no more sends the HTML representation if the message is entirely plain text.
• (#743) "Open/Join room" entry now ignores leading and trailing whitespaces.
• (fc2f971) Room display name disambiguation is a bit more prominent in the room tooltip (it was buried in the tooltip text before, now it's in the headline).
• (#783, thanks to @mymindstorm) Fix the SVG icon name to follow ECM conventions so that it actually gets installed.
• (cb44315) Fix some messages coming untranslated even though they have translations.
• (#415) The --debug option is no more - it did nothing for a few years by now, time to go (better debug options will arrive in 0.0.96).
• (a78ec9e, #788) Some preparatory changes to fix #782.