support rounding to significant figures instead of dp

[orbli]

as title. i just can't ctrl+F the word "significant" in the doc, probably some operation on exponent in decimal struct would work.

[paupino]

Hi @orbli, This is a good suggestion and wouldn't be too hard to implement. It isn't currently available in the API but could be implemented - it may need log10 support... I'd need to take a look into it. I'll take a look in the next few weeks - unless of course someone wants to grab it before then.