ENH: use growing/shrinking slices in resizing
ENH: use growing/shrinking slices in resizing

This change improves performance of resizing by working on the minimum
number of array entries.
Further, some minor doc and comment improvements are made.

kohr-h/odl,odlgroup/odl,aringh/odl,kohr-h/odl,odlgroup/odl,aringh/odl