[core] Adding more functions for timecube.
[core] Adding more functions for timecube.

openconnectome/open-connectome,neurodata/ndstore,neurodata/ndstore,neurodata/ndstore,openconnectome/open-connectome,neurodata/ndstore,openconnectome/open-connectome,openconnectome/open-connectome,openconnectome/open-connectome,openconnectome/open-connectome