[addons] change root of add-on manager to unsorted rather than sort by label
[addons] adds LastRepoUpdate() to the add-on installer
[addons] adds 'Check for updates' to the root of the add-ons manager.
[addons] show all add-ons in the add-on manager, including libraries/modules/helpers
[addons] set default to 'notify' rather than 'auto update'