Extend menu support

Hi,

I would like to request the following features regarding menus in tinymce_node_picker.

1.) Support for hidden menu items.
Rationale: we use hidden menu items for URL generation and of internal structure of our pages, therefore we would like that hidden menu items are shown under the "Menu" tab of tinymce_node_picker.
Implementation: I reckon it would be best to create an option on the settings page that makes it possible for end users to decide whether hidden menus are shown on the popup.

2.) Support for multiple menus.
Rationale: we use multiple menus to structure our pages, hence we would like to pick items from multiple menus in the tinymce_node_picker popup.
Implementation: Under the "Taxonomy" tab one is able to select the required vocabulary, I suggest a similar dropdown box to select a menu would do the job under the "Menu" tab.

Thanks in advance!