Remove 'colour' parameter from series initialisation

The colours are now controlled by the theme, so there is no need for the
series to have its own colour.
Theme controls axis linewidth

This was previously being controlled by style.css, when it should be
inbuilt into the library.
Remove opacity from CSS

Gives the bubbles, columns and rows control over their opacity. When
drawn, each series checks if it is selected/notselected, and adjusts
opacity as required.

Also cleans up some of the overridden properties in the insight.css