WebExtensions (Firefox) release

Added WebExtensions version + published to Firefox add-ons.

Published browser extensions:

• Chrome
• Firefox

Auto refresh styles on options change.

Styles are now auto refreshed when you change the emoji style.

Fix custom emoji.

Custom emoji are now excluded as we do not want to replace them (+they were rendered badly).

Updated graphic resources and wording.

v0.6

Update graphic resources

Initial commit

v0.5

Initial commit