Support Decimal type

[blais]

It would be quite useful and a propos to support Python's well-written Decimal type distinctly from floats natively. Lots of CSV files commonly contain financial data exported from other systems, data which includes precise numbers expressed as decimal numbers. Operations on these numbers (e.g., sum) should be carried out with Decimal aware operations. While applications such as models won't benefit much from this, applications that deal with accounting and finance will.

I'm not sure how involved the change is, would love to hear your thoughts on what would need to be done, whether it's feasible, difficult or easy, or even desirable. TYTY