Enhanced guess_bounds docstring.
Fix masked npy reference file creation.
MAINT: No further updates to changelog.

Currently the iris whatsnew purpose overlaps with the changelog and
thus the changelog has no clear purpose.  For developers it has been
agreed that for them to analyse the commit history would serve the
intended use of a changelog.
Merge pull request #760 from cpelley/rm_changes

MAINT: Remove iris changelog.
Created v1.5.0
Merge pull request #761 from pelson/v1.5.x

Created v1.5.0
Merge pull request #759 from rhattersley/fix-masked-npy-data

Fix masked npy reference file creation.
Merge pull request #756 from pp-mo/guess_bounds_reword

Enhanced guess_bounds docstring.
New array broadcast function and deprecation of broadcast_weights.

broadcast_weights requires an array to conform to. The new function
broadcast_to_shape requires only a shape tuple. This change is
motivated by the desire to avoid loading cube data payloads whenever
possible.
Default CF spherical earth radius.
Merge pull request #763 from bjlittle/earth_radius

Support CF spherical earth radius.
grib bounded level save bug fix
Modified weight generation functions to allow singleton dimensions.

Also added missing tests to ensure these cases are working correctly.
Merge pull request #764 from ajdawson/strided-broadcast

Add `broadcast_to_shape()` and deprecate `broadcast_weights()`.
Convert tests to use assertIsInstance.
Separate fill value from checksum
Merge pull request #766 from rhattersley/better-tests

Convert tests to use assertIsInstance.
Update test results.
Removed requirement for contiguous bounds in area_weights()
Merge pull request #715 from bblay/gribsavebound

grib bounded level save bug fix