Add empty 4.2.10 sql upgrade script, to avoid warnings during upgrade.
Bump versions to 4.2.10. (this was already OK in the tar.gz because of distmaker, but had not been committed to git)
CRM-12759 - Multisite add to group code doesn't kick in when a group is being added
CRM-11356 fix date range descriptors
CRM-12099 navigation tree problem