Handle invalid geometries

[rmarianski]

After quantizing and encoding mvt tiles, we can end up in situations where we generate invalid geometries. The encoder should allow for the flexibility to handle these in different ways, eg drop invalid geometries, try to correct the geometry and try again, raise an exception, etc. Offering a callback might be a general way to approach the implementation.

[rmarianski]

Related to #42

[nvkelso]

@rmarianski Anything more to test with this one before taking it to prod?

[rmarianski]

Good to go.