Quantiphy

- Include full quantities if available in *IncompatibleUnits* errors

- Added new standard SI scale factors (*Q*, *R*, *r*, *q*).
- Subclasses of `Quantity` with units now convert values to the desired units rather than allowing the units of the class to be overridden by those of the value.
- Added scale factor conversion.
- Added quantity functions: `as_real`, `as_tuple`, `render`, `fixed`, and `binary`.
- Fixed rendering of full precision numbers in `Quantity.fixed()`.
- Added *preferred_units* `Quantity` preference.
- Added “cover” option to *strip_radix* `Quantity` preference.
- Added type hints.

- Support parameterized unit conversions (such as molarity).
- Allow % to act as a scale factor.
- First argument of scaling functions are now guaranteed to be quantities.
- Added _UnitConversion.fixture_ decorator function.
- Added _UnitConversion.activate_ method (allows overridden converters to be re-activated).

- Refine the list of currency symbols.
- Allows currency symbols to be given before or after the underlying number.
- Allow _Quantity_ subclasses to be used in scaling if they have units.

- Add support for — as comment character and make it the default.

- Updated predefined physical constants to CODATA 2018 values.
- Switched to more permissive MIT license.
- Add feet to the available length/distance unit conversions.