Added IsANumber requirements for float and double to require that they
are not NaN
Even though it's argument values that are being tested, the name comes from
the parameter. Renamed ArgumentName to ParameterName in all tests.
Should create a better facility for that at some point.
Also changed all of them from hardcoded strings to random. As it were I could
have easily rewritten the code to always return "foo" as the parameter name and
all tests would still have passed.
0.9.3 release