Add binary option to stl codec

[Charlie-83]

Relevant issue: #29

I have added a binary option to the stl codec. This should be True or False

Default encoding is still ASCII for reasons discussed in the issue.

I have added a relevant test.

[jmwright]

@Charlie-83 This test has a method of checking binary file content, in case it's relevant here.

https://github.com/CadQuery/cq-cli/blob/main/tests/test_glb_codec.py#L46

[Charlie-83]

@jmwright Yeah, I did a very similar thing here. Just checking that the first 5 bytes aren't "solid" which would mean it was an ASCII stl. Wikipedia says that the binary format should never start with "solid".

Of course, the binary file could just be a load of nonsense. But, I'm guessing that actually parsing the contents to check it's cube is overkill. I could check that the number of triangles is correct or something since that's near the start of the file.

[jmwright]

@Charlie-83 Is this ready for review?

[Charlie-83]

@jmwright Yes, thanks

[jmwright]

Thanks for this @Charlie-83 !