(Finally) Implemented Run-Time Resolution Changes + Threading Fixes

[bryanedds]

So this got put off for quite a while, being implemented in bits and pieces over the years - #50

This was a pretty complicated thing to do given how much variation you can get between platforms and the fact that its representation requires the use of global mutable variables that just perfectly go against Nu's architectural intent.

Additionally, recent stability issues due to the new SemaphoreSlim-based renderer threading model have been addressed by effectively going back to the old volatile flags + spin yields threading model. It may not make as optimal utilization of the OS's scheduling resources, but at least it does hang itself when the window is minimized or cause 'random' hangs in the Visual Studio debugger.

Finally, during the refactoring process that enabled fixing #50, a few constants were refactored, resulting in VirtualScalar being renamed to DisplayScalar in your program's App.config file.

Finally, we've exposed support for public discussion in this github repository, with which a discussion for this release will be provided in case of any comments or questions!

Full Changelog: v17.9.0...v17.10.0

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This discussion was created from the release (Finally) Implemented Run-Time Resolution Changes + Threading Fixes.