Add association rules

New rules :
- A gite can not be linked to a route
- A parking can not be linked to a route if a main/sub parking is already linked to it
- A sub site can not be linked to more than one main site
- A site can not be linked to more than one summit
- A summit can not be linked to a sub site
- A sub summit can not be linked to more than one main summit
- A sub parking can not be linked to more than one main parking
debug gite association
Add association rules

New rules :
- A parking can not be linked to a hut if a main/sub parking is already linked to it
- A parking can not be linked to a site if a main/sub parking is already linked to it
imgur notice
C2C-global function
preview highlight (for modern browers)
i18n
disable outings wizard in mobile version
Merge branch 'master' into prod