layout designer interface API
This commit adds more methods to the public, stable API for the layout
designer dialog, allowing plugins and scripts greater flexibility
in extending and hooking into the layout designer.
New API includes:
- access to the main menus shown in the dialog, allowing custom actions
to be added to the dialog
- access to the dialog's toolbars
- methods for adding (and removing) additional dock widgets to the designer
- the method used to show/hide rulers in the designer
Checks whether a function declaration has parameters that are
top level const.
const values in declarations do not affect the signature of a
function, so they should not be put there.
