… part anymore
…ate regular expressions. These will be regenerated on first use. Remove specs for define!
…ts are defined according to their actual definitions. Rational scalars are also used when possible (and in some cases, values are approximated by their rational equivalents). This minimizes problems with round-off errors. In general it is much easier to read and understand the definitions, but recognize that some units need to be defined immediately so that they can be used to define other units. This ends up causing the parser to repeatedly call Unit.setup, which is still somewhat inefficient.
…exception fixes #27.