Convective Organisation Potential (COP) refactor

[leifdenby]

• [x] refactor code to make cloudmetrics.objects.metrics.cop.cop(object_labels=...)
• [x] implement all tests for figure 5 in White et al and ensure they pass
• [x] implement all tests for figure 4 in White et al

[martinjanssens]

I think I've sorted most of this now in https://github.com/martinjanssens/cloudmetrics/tree/cop. Both example fields for fig. 4 had slight mismatches wrt the figure presented in White et al. (2018). When making them correspond, fig. 4b) matches; fig. 4a) does not. @leifdenby you also noted (correctly, I think) in #42, that the authors might have copied the figure over with a small mistake. I'm inclined to use the value our algorithm now calculates for the figure shown in fig. 4a) of White et al. (2018), given we're quite confident the algorithm, which matches all other 10 examples, is right.

[leifdenby]

I think I've sorted most of this now in https://github.com/martinjanssens/cloudmetrics/tree/cop. Both example fields for fig. 4 had slight mismatches wrt the figure presented in White et al. (2018)

Thank you again!

@leifdenby you also noted (correctly, I think) in #42, that the authors might have copied the figure over with a small mistake. I'm inclined to use the value our algorithm now calculates for the figure shown in fig. 4a) of White et al. (2018), given we're quite confident the algorithm, which matches all other 10 examples, is right.

I agree. Thanks for checking this. I'll merge your branch and get this merged into master