Add .gds.gz support to read_gds() and shape tags and layer tags filtering to read_oas()

[walkerstop]

I am still learning how to build the tests so I have not tested these code changes enough yet, but I think everything is here.
From issue #280 (give read_oas() shape and label tags)
And issue #222 (support .gds.gz files in read_gds(), NOT supported for writing yet)

[walkerstop]

Is there any such thing as a regression test I can build to help validate these changes?
They work in my app but merging my changes with the latest gdstk changes and removing unwanted code changes was a lot of manual merging so I could have made some mistake somewhere.

[walkerstop]

Does anybody have an application that uses GDSTK as-is with no modification, that I could use to test my code changes more?

[heitzmann]

Hey @walkerstop sorry I never replied to this PR! I must have archived it from my inbox by mistake and I haven't been developing gdstk at all, so I hardly look at the repo anymore (unless I get specific PRs that I can work on in a couple of hours max). So, as you can tell, I don't have any large examples to use for testing your changes and reviewing it all will require quite some effort. THB I'm not sure how to proceed here unless we get someone else to help you reviewing and testing.