more changes, some for the better, some for the worse
A number of changes, primarily adding BigDecimal and BigDouble.
Merge branch 'master' of https://github.com/destenson/AlgebraCpp

Conflicts:
	Algebra/Math/Algebra.Internals/Algebra.cs
	Algebra/Math/Algebra.Internals/Expression.MakeExpressions.cs
	Algebra/Math/Algebra.Internals/Expression.Operations.cs
	Algebra/Math/Algebra.Internals/Expression.Test.cs
	Algebra/Math/Algebra.Internals/Expression.cs
	Algebra/Math/Algebra.Internals/ExpressionPair.cs
	Algebra/Math/Algebra.Internals/Function.cs
	Algebra/Math/Algebra.Internals/Operator.cs