Improve handling of healing code

[thomthom]

See #110. The slow down is due to the healing which is triggered by tiny faces being lost because they are too small for SketchUp's tolerance.

Look into improving the performance of healing.

Also look into providing a warning for very large models so the user is aware the operation might take a long time.

Perhaps detecting edges that are below SketchUp's tolerance would help in bailing from the healing method?

[jimfoltz]

Just a thought - have the importer always import at an exaggerated scale, then scale down to the user's selected units after?

[thomthom]

I was thinking of that. Though that could make for issues during copy and paste - you might end up with copies in the original scale of the definition. At least if the group is converted to a component and then picked from the component browser - which is not unlikely.

There's also the issue of all too large units triggering OpenGL clipping...

[thomthom]

Hmm... this keeps coming back. Blindly trying to heal will often lead to SketchUp freezing up for way too long.