Change the way colors are handled for syntax sections

[pgengler]

Currently syntax blocks work by specifying the color along with the regular expression to be matched. This should be changed so that instead of specifying the color, the regular expression is paired with a "type" string.

A new type of section in the .pinotrc file would map these "type" strings to colors.

The benefit of this is that it makes theming possible; multiple files providing different sets of colors can be provided but they all make use of the same regular expressions.