Neuron implementation work

[andrewgait]

Adding this as a PR to the neuron implementation project so that it doesn't get forgotten about...

[coveralls]

Pull Request Test Coverage Report for Build 589

• 10 of 11 (90.91%) changed or added relevant lines in 1 file are covered.
• 20 unchanged lines in 5 files lost coverage.
• Overall coverage decreased (-0.9%) to 90.758%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
spinn_utilities/classproperty.py	10	11	90.91%

Files with Coverage Reduction	New Missed Lines	%
spinn_utilities/ranged/abstract_list.py	1	99.6%
spinn_utilities/package_loader.py	2	74.51%
spinn_utilities/ranged/abstract_sized.py	2	92.23%
spinn_utilities/overrides.py	2	100.0%
spinn_utilities/log.py	13	64.2%

Totals
Change from base Build 568:	-0.9%
Covered Lines:	1905
Relevant Lines:	2099

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💛 - Coveralls