* Merge core libraries.
Everything below `Avalonia.Controls` into `Avalonia.Base`.
* Move new files to correct place.
* Removed unused dirs/projects,
* Removed outdated references from theme assemblies.
* Merge unit tests to match new assembly layout.
* Fixup test namespaces.
* Make directory match namespace.
* Move files to match namespace.
* Move files to match namespace.
* Fix up incorrect namespace.
`Avalonia.Visuals.Media.Imaging` -> `Avalonia.Media.Imaging`.
* Fix resource URL.
* Removed outdated dependencies.
* Added missing project reference.
* Update test namespaces.
* Fix merge error.
* Fix merge errors.
* Fix bad merge in WindowsInteropTest.csproj.
* Fix up merge errors in csprojs.
* Remove merged tests from nuke.
* Fix up namespace.
* Fix compile error.
* Fix failing tests.
Now that more unit tests are present in Avalonia.Base.UnitTests, general `AvaloniaObject` properties are getting registered. Ignore those.
Co-authored-by: Jumar Macato <16554748+jmacato@users.noreply.github.com>
The Nullable annotations on netstandard2.0 are incomplete and incorrect in places. Ignore nullable warnings on netstandard2.0 and make them errors on later target frameworks.
* Add nullable annotations...
...to `AvaloniaObject`/`AvaloniaProperty`-related classes and a few other uncontroversial files.
* Check for null before first use.
* Don't need this check as base class does it.
* fixes: suppress warning CS0659 Type overrides Object.Equals(object o) but does not override Object.GetHashCode()
* fixes: Warning CS0108 'AvaloniaXamlIlCompiler._configuration' hides inherited member 'XamlCompiler<IXamlILEmitter, XamlILNodeEmitResult>._configuration'. Use the new keyword if hiding was intended.
* fixes: Warning CS8765 Nullability of type of parameter 'obj' doesn't match overridden member.