Convert to a web extension

[whimboo]

We should check what's necessary to convert the memchaser restartless extension to a web extension.

Here some links:

• All about web extensions on MDN
• Web extensions guide and howto
• Linting + auto-reload after changes

[xabolcs]

At first sight the GUI comes to my mind: how to implement?

[whimboo]

We might have to go with a button on the toolbar first, which opens a popup containing our current toolbar content. Something as described here: https://developer.mozilla.org/en-US/Add-ons/WebExtensions/manifest.json/browser_action