Commented out un-finished ncx generation code
Added skeleton RemoveHeadingOperation
Implementing nav file updator
Added UpdateNavigationDocumentsOperation and a single unit test
Finished first sort-of-working version of the three operations: Insert/Remove/Update nav
Fixed getCurrentElement, selection efter insert and remove ops and added a bit of css
Moved image dimension function from operation to utils class
Merge pull request #28 from oleholstandersen/nota-783

Nota 783