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)

src/components/settings_modal/tabs/general_tab.js

@@ -50,6 +50,7 @@ const GeneralTab = {
       return this.$store.state.instance.background &&
         !this.$store.state.users.currentUser.background_image
     },
+    shout () { return this.$store.state.shout.channel.state === 'joined' }, 
     ...SharedComputedObject()
   }
 }