Major change to the interface for General_Base

Instantiation for Number types in Precision::General_Base now requires a
second pointer to another array with external linkage instead of using
nontype parameters.
This will hopefully give a bit more flexibility in what the image type
(CharT) may be. Although sacrificing readability and the forcing
external linkage, this change will make the number type system easier to
extend and neatly organizes the order of parameters in a consistent
manner (before the additions of slash and imaginary symbols made the
ordering confusing).

For more information on the new requirements, please refer to
Precision/General_Base/Precision_Int_General_Base.h

Other changes are cosmetic as in fixing typos and updating the template
parameter clarification documentation.