Update: implement f_number_signed and f_number_unsigned, as either 32-bit, 64-bit...

Update: implement f_number_signed and f_number_unsigned, as either 32-bit, 64-bit, or 128-bit

Provide the types f_number_signed and f_number_unsigned as a way to define the default "number" type to be used for string to number conversions and array indexes.
By providing 32-bit, 64-bit (default), and 128-bit types, the type can then be adjusted to more easily work on limited hardware or expand to more capable hardware.

This will be the recommended number data type to use in FLL functions going forward.