Merge pull request #14 from zenangst/master

Fix rendering bug when hovering change
Refactor interface
Change menu item title to match interface title
Remove whitespace
Rename Discrete to Subtle
Refactor interface (even moar)
Implement new git gutter setting in rendering code
Merge pull request #15 from zenangst/add-subtle-configuration

Thanks for this.. Add configuration for change the size of the gutter marks
Minor tidy-up ("verbose" gutter colours can be transparent)