1. Remove ItemDropEvent
2. Remove ShowContextMenus from API
3. Fix context menu item can't be opened ( #535 ), bug introduced from PR #494 (commit 45dbb50)
4. Move open result command and load context menu command back to
MainViewModel
5. unify load context menu logic
6. other performance enhancement and potential bug fixed
1. Fix "Remember launch location", this was introduced since e7aa6022.
Fix#511
2. Fix opening position ( #510 ), bug introduced from PR #494 (commit e7aa602)
1. Reorder the sequence of initialization of UserSettings.
2. Use dictionary for CustomizedPluginConfigs, so code logic like
`.FirstOrDefault(o => o.ID == id);` are removed
3. part of #389
- Add MVVM structure(BaseViewModel)
- Create ViewModel for MainWindow
- Refactor MainWindow.xaml to support MVVM
- Move PublicAPI implementation from MainViewModel to PublicAPIInstance