checks for changed tags
Merge branch 'dangoor/4948-tag-change' into dangoor/4948-tag-change2
Comment improvements
Updated implementation of elementReplace.

This implementation works for void elements and is actually simpler than
the old one.
New mechanism for determining tag changes.

Tag changes are now spotted when IDs are assigned and given new IDs,
allowing all of the normal insert/delete machinery to work. This
also fixes a bug when inserting elements in between unchanged
text nodes.
Testing tag change with child elements.

Also added comments for the new fixupElementInsert function
Formatting tweak to make jshint happy.
Minor cleanup after reviewing the tag change code
Cleanup from code review.

Comments and using this.getNewID() rather than tagID++
Merge branch 'master' into dangoor/4948-tag-change2
Renamed addBeforeID to finalizeNewEdits
Merge pull request #4983 from adobe/dangoor/4948-tag-change2

Fix for 4948: changing tags (based on master)