solarized: fix contrast and warningmsg

Improved overall contrast of solarized theme. See image (first line is how it was, second line is fixed):
![change](https://f.cloud.github.com/assets/674812/1016411/57a6f5b8-0bf9-11e3-865a-7c79e63a6c04.png)

Also, fixed issue with incorrect warningmsg field highlight:
![warn](https://f.cloud.github.com/assets/674812/1016413/68871336-0bf9-11e3-8c46-085ca139a5c2.png)