Update to master of VE core

New changes:
1f7e944 Add method to fully destroy a target
6cda4b7 Fix scrolling back and forth on copy/paste in Firefox
34d2c79 demos: Support back/forward navigation
787deba Replace dump model loop with event triggered dump
94b1b40 Do not use global document
5cd4227 Always use current surface on demo page
f74f6d8 Make DefinitionListItemNodes splittable

Change-Id: If0a7beed97c4fa6759fbbb989d7ef979c0a1e4e2