Release Process 1.9.9

This release on the 1.9 branch is motivated by 2 improvements, first the release-check and also various security fixes as we had 3 diffferent analysts that reported security flaws to the security group, approximatively the same day, which is quite convenient. As this is a security release, it's done quite fast in emergency.

This release process began 3 days ago with security reports, handled by the security group, under release management of mose.

Release checks

This new feature adds 2 options in general admin panel, to enable/disable remote checks and to setup the frequecy of those checks. The checking of a new version is done with a simple http request on tikiwiki.org site, when someone with admin perms displays any admin panel.
When the check is done and a new version is found, a message is displayed in admin panels to warn there is something new, and then no further checks are performed anymore (until upgrade).
This feature is enabled by default, which is motivated by the fact that we know that people don't usually follow the Tikiwiki community activity and they take time to upgrade