Fix bad rules in themes, measure width correctly.

This will make fixedGutter work properly, and make it the only model
(no more gutter that scrolls out of view).

Also reorganizes the basic css file to be easier to modify for users.

Issue #730

Courtesy of Mike Griffin

Issue #432

Otherwise, you'd get a cursor/text misalignment in some fonts.

Standardize theme, add links to front page and compression helper.

So that it doesn't make selected text unreadable.

It's tiny anyway, no need to force people to include yet another file.

Signed-off-by: Jan Keromnes <janx@linux.com>

Courtesy of Joshua Maxwell

Closes #227

Signed-off-by: Jan Keromnes <janx@linux.com>

This normalizes the classes used by most of the modes
(reStructuredText and diff didn't fit in), and makes them all
reference a central style sheet (under theme/). It also adds a theme
option that can be set to change the theme, and defines a few
different themes (some based on old mode colors).