Removed ProgressEventHandler

I shouldn't have added / used it in the first place
Progress<T> fix (added "NewEventHandler")

Avoid using EventHandler<T> explicitly with Progress<T>, I repeat:
Avoid!
Improved Disposing

_handle gets disposed, I assure you.
Readme updates
Naming convention fix
Naming convention fix

I have to continue fixing style in BigInteger
Also there are things to improve here
Added TODO in WorkContext

A dedicated thread may die because of an unhandled exception. I will
probably keep it alive instead of cycling a new one.
Added CencellationToken et al.
Tweak to ThreadingHelper to match Mono's SpinWait
Added SpinWait
Readme updates (again)
Code analysis fix in GCMonitor
Style fixes
Style fix [for (;;) -> while(true)]

Because some tools think that ";;" is weird.
Enforcing naming convention

Renamed private static readonly fields to be "_" followed by lower camel
case.
Global Clean Up

Removing unused using and empty lines.
Refactored ThreadinHelper SpinWait into T4

ThreadingHelper SpinWait methods are now generated from a tt file.
Added new method SpinWaitExchangeRelativeUnlessNegative to help with
CountdownEvent
Added new overload and improved performance
Changed members to internal for use in SpinWait
ThreadingHelper.SpinWait small improvement

Converting double to long early this should mean better performance
SpinWait implemented by calling ThreadingHelper