[Unstable]: MEF refactoring
Merge branch 'unstable' of github.com:antigravity/Wox into unstable

Conflicts:
	Wox.Core.Data/UserSelectedRecordStorage.cs
	Wox.Core/GlobalHotkey.cs
	Wox.Plugins.Calculator/CalculatorPlugin.cs
	Wox.Plugins.Url/UrlPlugin.cs
	Wox.Plugins/ActionContext.cs
	Wox.Plugins/IPlugin.cs
	Wox.Plugins/IPluginContext.cs
	Wox.Plugins/IPluginMetadata.cs
	Wox.Plugins/ISettingProvider.cs
	Wox.Plugins/PluginBase.cs
	Wox.Plugins/PluginContextBase.cs
	Wox.Plugins/Properties/Annotations.cs
	Wox.Plugins/Query.cs
	Wox/PluginLoader.cs
	Wox/PluginManager.cs
	Wox/UI/Controls/ResultPanel.xaml.cs
	Wox/UI/MainWindow.xaml.cs