* Removed massive demo folder from the extension, which brings down the size from 2.5MB (!) to 8K.

The reason for this is that the repo contains a "demo" folder with a reasonably big gif file which was not being ignore when generating the extension from the code.

The new command to generate the extension build is `web-ext build -i demo`.

Fixed the following issues:
- Layout setting is lost even when the page is not refreshed (https://github.com/timmyjose-projects/layout-trello-ff/issues/2)
- Focus is lost from "new list" template at the bottom of the flex box in "mixed-mode" layout (https://github.com/timmyjose-projects/layout-trello-ff/issues/1)