lots of keybinding changes.  added a new action to allow removing markers at the playhead location.  numpad now allows you to access marks higher than 9.  to locate to a marker, use the numpad decimal to start and end the operation - for example press .19. to locate to marker 19.   also added alternate bindings for redo, delete, and several other alternates that will be needed in subsequent commits.   tab is not working, using either Tab or nabla in the binding.in file