Created a simple object to keep two properties of different types bound together. It is a bit quirky because it has to deal with some weirdness of the original classes, but I found it useful
updated comments and expanded some tests regarding HeterogeneousBidirectionalBinder, ready for merging
Merge pull request #96 from CarrKnight/8.0

Merging my own pull. And now I just sit here and wait for the bug reports to roll in.