Resolve the multitude of Measures implementations

The file [Measures.cs](https://github.com/atmoos/Quantities/blob/master/quantities/measures/Measures.cs) contains way too many measure implementations.

This concept needs to be revisited.

Start by reading quantities/measures/Measures.cs and inventory the measure implementations it contains. The issue does not define the replacement design or acceptance criteria, so clarify the intended concept and scope before changing the file; done would mean an agreed, maintainable measure structure.

Written by the indexing model from the issue text.