Fix issue where python's sys.module dict fails to convert to a MATLAB dictionary

[ehennestad]

Fix issue #68

The following line in Zarr/pySetup attempts to convert the sys.modules python dict to a MATLAB dictionary.

MATLAB-support-for-Zarr-files/Zarr.m

Line 52 in 0c96a28

loadedModules = dictionary(sys.modules);

When running this, I get the following error:

Error using six>__get__
Python Error: AttributeError: 'NoneType' object has no attribute 'BaseHTTPServer'

I have not explored why, but I assume I have a python module installed which fails to convert to a MATLAB type.

Here I propose to only convert the keys of the dict to a string array and check if ZarrPy is part if that array. I also added try catch to ensure there is a fallback if the check fails.

[ehennestad]

An alternative that uses python instead of converting to MATLAB types:

pyContainsModuleFcn = py.getattr(sys.modules, '__contains__');
requiresZarrPyReload = ~pyContainsModuleFcn("ZarrPy");

[krisfed]

Hello Eivind,

Thank you for your interest in the project - for creating issues and for this pull request!

Apologies for the issues with pySetup - I was hoping to rework this logic there sometime soon as well. But happy to merge this in the meantime (and to receive any future pull requests!).

We will need to send you a CLA to sign as part of the policy if this is your first submission to the MathWorks github organization. I will reach out by email to handle that.