Add a Decimal Number Type

[jbourquin]

A decimal number type serialized as a string would allow for an 'exact' representation of a floating point number. This would be very beneficial to monetary applications or applications that require significant decimal places in the number.

It would also help developers avoid errors in the way the binary floats are represented across different systems:

i.e. 3.3 == 3.3000000000000003

[tarcieri]

I have definitely considered this in the past. Thanks for opening an issue about it.