This splits indexing into two phases:
* preindex (where only pages, space lua, space styles are indexed)
* index (where everything else is indexed)
The goal is to get to more-or-less operational state quicker this way,
because probably most functionality can already be enabled after the
pre-index phase.
Last openen page information is now kept in the datastore and therefore
persistent even across tabs. This seems to also have fixed ther andom
behavior when deleting a page -> you always go back to your last opened
page (before the one you deleted).
Zef Hemel