(core) reworked video framesets to use vstores

This refactor is rather intense in terms of possible
impact, most important cases have been tested but a
long string of corners to cover. The idea is to cut
down on vobject- references and use smaller blocks,
e.g. struct storage_info_t.

This accidentally fixes one out of several multitexturing
issues. Round-robin storage still unconfirmed though.