minor, go for 8 adjacent mut_oid_t values in hash, rehash upon 8-folding
minor, rehash on every resize of ftmap
minor, refactor timeline checking and resizing into separate routines
minor, employ doubling technique for timeline resizes
Merge branch 'backend/mem'

* backend/mem:
  minor, employ doubling technique for timeline resizes
  minor, refactor timeline checking and resizing into separate routines
  minor, rehash on every resize of ftmap
  minor, go for 8 adjacent mut_oid_t values in hash, rehash upon 8-folding