Aiming at a 100% compatible, drop in replacement for Linq-to-Objects that is, mostly, faster!

In my spare time I have been working on this project for a number of years, originally as a replacement for F#'s Seq, and more recently as a placement for System.Linq.

So although I have tried to get those PRs mainlined, understandably the project owners have balked at the implied risk associated with such a venture. (And really this is just a spare time thing for me so I haven't had the time to keep pushing...)

The code was originally from on the corefx System.Linq code for bootstrapping - the vast bulk of the code has been rewritten, except for the tests and some algorithmic code (i.e. sorting).