Fixesshaarli/Shaarli#29
Style elements refactored as follows:
- use existing ids and classes if possible,
- else, define new ones and stick with the existing naming convention,
- remove hardcoded style attributes from RainTPL templates.
Exception:
In tpl/tagcloud.html, the display size of each tag is computed at page
generation.
Signed-off-by: VirtualTam <virtualtam@flibidi.org>