Improve string representations of customised objects

[ortk95]

String representations (e.g. from str() or repr()) of objects now include any extra arguments used to customise the object. These arguments are only included in the string if they have been changed from their default values, keeping the string concise. For example:

body = planetmapper.Body('JUPITER', '2000-01-01T00:00:00.000000', observer='EARTH', illumination_source='Europa')

# New behaviour:
print(body)
# Body('JUPITER', '2000-01-01T00:00:00.000000', observer='EARTH', illumination_source='Europa')

# Old behaviour (note the customised illumination source was missing):
print(body)
# Body('JUPITER', '2000-01-01T00:00:00.000000', observer='EARTH')

This is implemented for all objects by defining a (private) dictionary of the default argument values used to initialise the object, then using this to automatically include non-default arguments in the string. Therefore, any new objetcs/subclasses simply need to add any new arguments to _get_default_init_kwargs, then _generate_repr can be used to automatically generate a desired string.

Closes #351.

Pull request checklist

• [x] Add a clear description of the change
• [x] Add any new tests needed
• [x] Run spell check on new text visible to user (documentation, GUI etc.)
• [x] Check any changes to requirements.txt are reflected in setup.py and conda-forge feedstock
• [x] Check code passes CI checks (run run_ci.sh or check GitHub Actions)

See CONTRIBUTING.md for more details.

[coveralls]

Pull Request Test Coverage Report for Build 9480386153

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This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 58 of 59 (98.31%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.02%) to 99.561%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
planetmapper/base.py	26	27	96.3%
<!--	Total:	58	59	98.31%	-->

Totals
Change from base Build 9416842717:	-0.02%
Covered Lines:	2955
Relevant Lines:	2968

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💛 - Coveralls