Algebraically simplify multiplication by i and -i.
Merge pull request #64 from pjonsson/complex-mul

Algebraically simplify multiplication by i and -i.
Remove redundant import
Add compile time check for signedness
Improve documentation
Add bit combinators
Add support for Double
Remove ambiguous constraint
Generalize unpair
Add printExprWith.
Merge pull request #65 from pjonsson/printExprWith

Add printExprWith.