New Olex2 update mirror

Thanks to John Warren we now have an external mirror for olex2 updates. A new version of Olex2 will have the mirror in the 'Update Options' dialog as well as in the list of repositories accessible from Olex2 Windows installer. Please use this repository if the main Olex2 website is down. For Linux/Mac users, this repository have to be set in the usettings.dat file as follow: repository=http://www.x-rayman.co.uk/olex2/olex-distro-test/update/