Several fixes

Hi,
Many things here. Sorry, I'm too lazy tonight to create several PR :smile: 

* CSS improvements and clean up (with and without [CSSLisible](https://github.com/Darklg/CSSLisible)): lot of changes
* Fix #16
* Fix shaarli icon display in new article toolbar
* Fix color of some icons in solarized and solarized-dark themes
  * bad-display.png
  * clock.png
  * flattr.png
  * link.png
* Add more space between articles