* Touch.Client references the official NUnitLite package, which means we're using
a non-forked version of NUnit.
* This makes it easier for our .NET 5 effort, since we won't have to port an ancient
version of NUnitLite to .NET 5 (nor will we have to keep using it in our existing
code, we can use more modern NUnit patterns).
* Reference MonoTouch.Dialog from the NuGet package. This also eases the .NET 5 effort,
since we won't have to port MonoTouch.Dialog to .NET 5 (we'll probably still do it
though at some point, but it doesn't have to be done right away), nor build it
ourselves / ship it.
Goals
* Reflect Apple nullability annotations in our bindings using C#8
* No warnings when building bindings
Non-Goals
* Update (add or fix) `[NullAllowed]` to match Apple headers (next phase)
* Make the generator or internal code fully nullable aware (`nowarn` is used)
Notes
* Apple's own annotations are not 100% accurate :(
* Where known issue exists we have _fixed_ our attributes to match reality :)
* We also do additional null-checks internally that might seems not required (better safe than sorry).
Rolf Bjarne Kvinge
Sebastien Pouliot