Moved getShortcutKeyAction() to VimShortcutKeyAction.getInstance()
Removed unused code
Extracted and inlined some variables
Removed unused DelegateCommandListener

There are no more actions marked with Command.FLAG_DELEGATE.
Inferred nullity annotations
Introduced EventFacade for subscribing to IDE events
Extracted EventFacade.*DocumentListener()
Extracted EventFacade.addEditorFactoryListener()
Extracted EventFacade.(un)registerCustomShortcutSet()
Extracted more EventFacade methods