Update VE core submodule to master (cf1e167)

New changes:
776e801 Delimit text nodes in debug observations
72643bc Remove debug bar hiding now it is handled by the surface
cf1e167 [BREAKING CHANGE] Multiple surface support and demo

Local changes:
Account for detachable toolbars in core being setup in a different order.

Change-Id: I29156948711d55ba5f6dd4f6c35ca0e4cca32373