added options to svg export

[shimwell]

Proposed changes

This PR updates the export svg methods so that they allow new export options such as view angle and image width.

The animation examples script has also been updated to make use of this improved feature.

Ideally the gif made for the rotation should have their last and first frame blend into each other but I've not quite got the angles x,y,z correct

This makes use of quite a new feature in CQ so the docker image usedin circle ci might need rebuilding for this to pass

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Code refactoring
• Documentation Update (if none of the other choices apply)
• New tests

Checklist

• Pep8 applied
• Unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[shimwell]

Now with showHidden=False

strokeWidth=6

Now with showHidden=False and strokeWidth=None

height, width, marginTop, marginLeft settings can be used to make longer gifs still relatively small file size

Thanks to @jmwright for upgrading the svg feature in the newest release of CadQuery 2.1

[jmwright]

Wow! That's an excellent use of that new feature, and the animation script is really interesting. Thanks for letting me know.

[shimwell]

merging into a temporary branch to combine with the updated stp and stl exporters