Completely overhauled solarized theme.

Colours now remain the same in all modes except for the outer segment
backgrounds.
Less use of solarized accent colours as backgrounds.
Clearer window separator colours.
Refactored source.
Mode background colours are now closer to blue to contrast less
with the body text background.

![airlinesolarizedmockup](https://f.cloud.github.com/assets/378622/768607/8c09f644-e8a3-11e2-9f7d-f2deebe8cb14.png)
Merge pull request #53 from Nextil/solarized-theme

Completely overhauled solarized theme.