Change functionality of read_array so it returns multiple variables

[Suizer98]

To address #77

After modifying this will enable us to perform:

variables = ["longitude", "latitude", "time"]
result = nco.ncks(
    input="sample.nc", options=["-v " + ",".join(variables)], returnArray=variables
)

lon = result["longitude"][:]
lat = result["latitude"][:]
...

so we don't have to call returnArray=[] one by one.

[czender]

@Suizer98 Thank you for your patch. As you can see, the same error occurs in all the above test results. It looks like a test fails to find a variable that presumably it used to find. Please update your branch/PR and ping me when it's ready to retest. There is also a deprecation warning that I do not recall seeing before. It likely has nothing to do with your branch. Feel free to fix that at the same time if you want, otherwise I'll give it a try.

[Suizer98]

@Suizer98 Thank you for your patch. As you can see, the same error occurs in all the above test results. It looks like a test fails to find a variable that presumably it used to find. Please update your branch/PR and ping me when it's ready to retest. There is also a deprecation warning that I do not recall seeing before. It likely has nothing to do with your branch. Feel free to fix that at the same time if you want, otherwise I'll give it a try.

Looks like the new changes only recognize list of strings instead of single string, I will try to add a new condition in a new commit.

[czender]

@Suizer98 Looks like good progress before a new issues arises...

[Suizer98]

I amended the commit accordingly and ran pytest to ensure that the changes didn't introduce any new issues. Everything should appear to be functioning as expected now. Feel free to check.

I made sure the classic way read_array works as usual:

result = nco.ncks(
    input="fake-trim.nc", returnArray="longitude"
)

[czender]

You did it. Touchdown! Many thanks for your contribution.