Fixing object array indexing issue
Add Changelog entry for recently merged pull request 269.  Regenerate
netCDF4.c.
Merge pull request #268 from rzlee/master

Fixing object array indexing issue
add Changelog entry for just merged pull request 270.  Regenerate
netCDF4.c.
Make netcdftime.datetime immutable and hashable. Fixes #255.
Merge pull request #275 from ddasilva/immutable-datetime

Make netcdftime.datetime immutable and hashable. Fixes #255.
add Changelog entry for pull request 275.
fix typo