feat(mono): native interactive f(x,y) 3D surfaces in Linux WinForms - #296

'TestServer.TestServer(IWebHostBuilder)' is obsolete: 'IWebHost, which this method uses, is obsolete. Use one of the ctors that takes an IServiceProvider instead. For more information, visit https://aka.ms/aspnet/deprecate/008.' (https://aka.ms/aspnet/deprecate/008)

'WebHostBuilder' is obsolete: 'WebHostBuilder is deprecated in favor of HostBuilder and WebApplicationBuilder. For more information, visit https://aka.ms/aspnet/deprecate/004.' (https://aka.ms/aspnet/deprecate/004)

'Scintilla.CaretLineVisible' is obsolete: 'Use CaretLineBackColor with alpha channel instead.'

The field 'ToolStripRadioButtonMenuItem.mouseHoverState' is assigned but its value is never used

The field 'ToolStripRadioButtonMenuItem.mouseDownState' is assigned but its value is never used

Non-nullable field '_tslCompiler' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Possible null reference return.

Possible null reference return.

Possible null reference return.