New user option: Hide floating shoutbox

The issue: I don't like clutter. I like control. Sometimes I wanna hide the shoutbox and have a clean UI.

The code: This adds a setting to hide the floating shout panel. Simple as. The setting name will show the name of the shoutbox set in i18n. All the code does is check for the setting and hide the panel if the option is set

Screens (showing on my instance, where I call the shoutbox "Nya~box")

Disabled (see bottom right corner)

Enabled (see bottom right corner)

CHANGELOG.md

@@ -9,6 +9,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Added option to mark posts as sensitive by default
 - Added quick filters for notifications
 - Implemented user option to change sidebar position to the right side
+- Implemented user option to hide floating shout panel
 
 
 ## [2.3.0] - 2021-03-01