Need support for Ctrl+Shift+Backspace keybinding

[okia]

Ctrl+Shift+Backspace (delete entire line) is a popular keybinding and we should support it. Emulate Emacs behavior with respect to existing selection, i.e. if multiple lines are selected while Ctrl+Shift+Backspace has been pressed:

• Remove the selection
• Delete only one [current] line

[savioret]

What about just using an existing action bound to a key ? The only difference is that this approach does not remove the current selection. At least is a temporary solution until the author accepts the pull request.

	{ 	"key": "ctrl+shift+backspace",
		"command": "editor.action.deleteLines",
                "when": "editorTextFocus && !editorReadonly" 
	},