parentElement is not defined on non-Element nodes in IE10

To have a "blanket rule", just use parentNode everywhere to prevent future problems,
as it is equivalent to parentElement for all practical usages.
navigator.language does not exist on IE10, so check for it as well
Handle IE10 obv. destructing event objects once the event handler is done
Merge pull request #718 from kossebau/smallFixesForIE10

Small fixes for IE10
Be more verbose in the About dialog of ViewerJS, not on toolbar
Merge pull request #719 from kossebau/moreInfoInViewerJSAboutDialog

Be more verbose in the About dialog of ViewerJS, not on toolbar
Add ChangeLog.md
Merge pull request #721 from kossebau/addChangeLog.md

Add ChangeLog.md
Enable reaching the Viewer's About dialog close button in small windows
Clean-up np longer needed build target viewerbuilddir-target
Merge pull request #716 from kossebau/fixViewerAboutDialogUncloseable

Enable reaching the Viewer's About dialog close button in small windows
Fix broken copying of dijit*.css
Merge pull request #725 from kossebau/fixBrokenDijitCopying

Fix broken copying of dijit*.css
Allow multiple instances of the editor to be created in a single page

Mangle HTML ids in a predictable fashion in dialog widgets to ensure they
do not clash if multiple instances are loaded.
Split screen editing app

Creates two editor instances within a single web-page, and allows live
collaboration between them.

Key features:
* EASY TO USE (requires no additional setup to run)
* supports client disconnection
* simplistic latency simulation
fixup! Split screen editing app

Cleaning up display slightly