Replaced the colour strip with a coloured bar graph.

This removes the thin full-colour stripe, and instead changes the background bar-graph to use a grayed version of the colours. This avoids issues where e.g. Firefox's colour/stripe clashes with the No cells' colour.
Altered the JavaScriptCore and BESEN colour-coding

BESEN is now a brown matching its broom logo. JavaScriptCore is now a tad bluer to differentiate it from the current browser bar.
Merge pull request #272 from webbedspace/enginecolours

Replace the colour strip with a coloured bar graph