Provide option to Field.dump to not display the first and last data values

[davidhassell]

Fixes #345

[sadielbartholomew]

Good idea. It works and everything looks good implementation wise.

My main comment is that we might want to include the units in the data line, given for print(f) and f (i.e. str and repr) they don't show the data but do indicate the units, however one could argue the units are shown in the global properties so that's sufficient. Will leave it up to you.

>>> f
<Field: air_temperature(atmosphere_hybrid_height_coordinate(1), grid_latitude(10), grid_longitude(9)) K>
>>> print(f)
Field: air_temperature (ncvar%ta)
---------------------------------
Data            : air_temperature(atmosphere_hybrid_height_coordinate(1), grid_latitude(10), grid_longitude(9)) K
...
>>> f.dump(display=True, data=False)
---------------------------------
Field: air_temperature (ncvar%ta)
---------------------------------
Conventions = 'CF-1.12'
project = 'research'
standard_name = 'air_temperature'
units = 'K'

Data(atmosphere_hybrid_height_coordinate(1), grid_latitude(10), grid_longitude(9)) [add unit symbol here e.g. K as per the above reports?]
...

Also, ideally you can update the second-line docstring description for dump so that "... and provides selected values of all data arrays." is qualified with something like "... unless requested otherwise"/"optionally excluding the variable data" (at the end) given this new argument.

Please merge when considered.

[davidhassell]

Hi Sadie,

we might want to include the units in the data line

That's a good idea: e42e09c

[sadielbartholomew]

Thanks for addressing the minor feedback/suggestion. Sanity check done on the new commits. All good, please merge.