Create Themed charts

[peter-mouland]

• [x] setup Theme mechanism
• [x] convert default to ft theme
• [x] apply Theme to titles
• [x] apply Theme to key
• [x] apply Theme to chart
• [x] run regression tests
• [x] document themes
• [x] remove styling from css

[radiodario]

Looks good to go! great to have gotten rid of those extra CSS files 👍