1.0-beta.1

• added folder select dialog
• added application menu for macOS apps. Accessible with the MacApplication.AppMenu property
• added BridgeObjectAttribute. It can be used to give a bridge object a custom name that is used to access it from the client side. By default (i.e. without the attribute), the class name is used.
• added a SynchronizationContext for each platform. It is automatically installed on the startup thread and ensures (among other things) that async/await works as expected
• added a list of opened windows. Accessible with the Application.OpenWindows property
• the localhost ContentServer used by the IE webview now uses one instance per app and not per window anymore
• replace ContextMenu class with ContextMenuStrip for Windows Forms (necessary for .NET Core 3.1 support)
• for better security, a crypto RNG is used to generate random resource URLs
• update/add publish scripts for the example and playground projects (for all platforms)
• implemented usage of custom ObjectiveC classes properly
• removed unnecessary STAThread attribute on Linux and macOS application entry points
• fix usage of the wrong native event backing Window.Shown on macOS
• fix and add basic support for SetWindowState on macOS
• several other small cleanups and fixes