Add R# annotations
Replace T4 templating with PowerShell templating

Easier to add and maintain the units. No dependency on Visual Studio.

* Add powershell script and include files
* Add unit definitions in JSON with prefix support
* Delete oboslete files related to old T4 templating system

Breaking changes:
* Delete OtherUnit, move Table/teaspoon into Volume
* Rename month and year units
* Fix plural naming of
** Pressure.KilogramsForcePerSquareCentimeterInOnePascal
** Ratio.PartsPer-units

Other changes:
* Support custom tolerance per unit in tests
* Move code more consistently into Custom/GeneratedCode folders
* Fix misc R# warnings
R# code cleanup
Fix test by increasing tolerance for Nanogram unit