A big-decimal implementation in C#.

• This BigDecimal implementation was inspired by another BigDecimal implementation (https://gist.github.com/nberardi/2667136) and Microsoft's BigRational (https://bcl.codeplex.com/wikipage?title=BigRational).
• The BigDecimal by nberardi lacks all mathematical operator overloadings and are therefor not very useful.
• This BigDecimal implements most of the methods in BigRational.

After the first version of this BigDecimal, I found another implementation (http://uberscraper.blogspot.se/2013/09/c-bigdecimal-class-from-stackoverflow.html) that probably is just as good.