Adding more metrics

[m-mohr]

The following was in this repository originally, before I simplified it to get an initial release out:

Property Name	Type	Description
metrics:width	float
metrics:height	float
metrics:micd	float	The Circumference-Area ratio (CA ratio) is calculated by dividing the circumference of a given polygon by the square root of its area. This ratio is then adjusted so that a circle corresponds to 0, and scaled so that a square corresponds to 1
metrics:ca_ratio	float