Simplify and reword the Complex form.

The Inline Entity Form field options need simplifying. At the moment end users can be confused by the amount of buttons to click and the current wording used on them.

At the moment there's an unnecessary 3 click process to adding an existing node.

1. Click 'Add existing node' button
2. Select an existing node from the select list (get patch to add select list) or type the node name in the autocomplete field
3. Commit the selection by clicking the 'Add node' button

2 of these clicks could be eliminated by simply having the select list appear in default mode of the field's form and if the user needs to create a new node then they just click on the 'Add new node' button. (Also, the wording on the 'Add new node' button is also confusing because the user is actually creating a new node in the system so a suggestion would be to have that button say 'Create new node' instead.)