minor, provide _get_as_of_then() using bdb cursors
test, provide regression case for bdb as-of-then time slice query
minor, provide supersede routine for berkdb backend
test, add regression file for supersedure in berkdb store
minor, provide hist routine for berkdb backend
test, add regression file for hist query in berkdb store
Merge branch 'backend/berkdb'

* backend/berkdb:
  test, add regression file for hist query in berkdb store
  minor, provide hist routine for berkdb backend
  test, add regression file for supersedure in berkdb store
  minor, provide supersede routine for berkdb backend
  test, provide regression case for bdb as-of-then time slice query
  minor, provide _get_as_of_then() using bdb cursors
minor, allow date value without time value
minor, use 64k page size in bitte-mem
minor, use TID_NOT_FOUND and reserve FACT_NOT_FOUND for a fact literal
minor, rewrite ftmaps as hash tables
minor, allow lazy init'ting of ftmaps
minor, initialise cache pages as-you-go
minor, only look 64 slots to the right upon hash collision
minor, perform rehashing when array grew 64fold
minor, also adapt rehasher to only look 64 elements to the right
fix, PEBKAC, return first transaction in ftmap_get_first()
test, sort results in rtr query because the hash table does not preserve insertion order
test, import rolf-pump tests to have a tool for mass data insertion
Merge branch 'backend/mem'

* backend/mem:
  test, import rolf-pump tests to have a tool for mass data insertion
  test, sort results in rtr query because the hash table does not preserve insertion order
  fix, PEBKAC, return first transaction in ftmap_get_first()
  minor, also adapt rehasher to only look 64 elements to the right
  minor, perform rehashing when array grew 64fold
  minor, only look 64 slots to the right upon hash collision
  minor, initialise cache pages as-you-go
  minor, allow lazy init'ting of ftmaps
  minor, rewrite ftmaps as hash tables
  minor, use TID_NOT_FOUND and reserve FACT_NOT_FOUND for a fact literal
  minor, use 64k page size in bitte-mem
  minor, allow date value without time value