This commit refactors code from the markdown lexer into the chroma
package, and alters the PostgreSQL and CQL lexers to make use of it.
Additionally, an example markdown with the various sublexers is added.
- Styles now use a builder system, to enforce immutability of styles.
- Corrected and cleaned up how style inheritance works.
- Added a brightening function to colours
- HTML formatter will now automatically pick line and highlight colours
if they are not provided in the style. This is done by slightly
darkening or lightening.
Fixes#21.
This is to solve an issue where writers returned by the Formatter
were often stateful, but this fact was not obvious to the API consumer,
and failed in interesting ways.
