Checks every 1.2 seconds which messages needs colouring and does el colouring.

Makes APL-XX code blocks linkable to linear.app

• multiple options of emoji
• reaction selector & colour

Firefox options:

• Firefox needs nightly/dev with "xpinstall.signatures.required" false, and package it with web-ext build

• Install from the releases on nightly/dev (.zip)

• Install the .xpi for standard firefox users

Chromium options:

• Load an unpacked plugin in developer mode.