Summary:
Add general support for composite distances and remove ad-hoc feet/inch-specific rules.
Test cases are added to the corpus.
This implementation resolves the ambiguous "m" unit to either Metric or Imperial units
based on context.
Reviewed By: patapizza
Differential Revision: D13911040
fbshipit-source-id: e75fd237158fc1c2f02709dfe4dd2f1907958b4c
