Add infrastructure for doing relation type stats
Create relation member and role stats
Auto indent
Add db indexes for relation types and roles
Fix relation role stats output.
Extract prevalent relation member roles.
Add data on all relation types to relation_types table
Add new relations section

There is a whole new relations section which gives information about different
relation types. There is a list of all relation types and there is a page for
each relation type which currently contains an empty overview tab and a roles
tab with a list of roles used with this relation type. There is currently no
link that leads to this section as it is not finished yet.
Show "no info" message when we don't have infos about roles.
Fix language comparison table
Improve regex for bad chars in url paths
Remove some functions from ruby code.

Those pretty print and link functions are available in Javascript, too. To
avoid code duplication, I changed the few places where those functions were
used to use the Javascript ones.
Code cleanup
Remove HTML comments from wiki pages