Tinkered with docs.
Sorted names in BinaryOperator enumeration.
Sorted names in UnaryOperator.
Streamlined UGenMethodMixin.
Added synthdeftools.Op.

Op will house static methods to perform unary and binary operations on UGens
and UGen arrays. This will provide a single point for documentation and tests.

UnaryOpUGen and BinaryOpUGen can then allow for optimizations keyed on their
special index via their _new_single() class method.