Schedule UI updates using requestAnimationFrame rather than setTimeout

Using requestAnimationFrame ensures the callback is executed prior to
the next redraw, eliminating undesirable & highly visible flickers for
UI updates.

Fixes issue #491.
Reduce UI flicker on FF as well

FF doesn't execute requestAnimationFrame requests before it's next
repaint, causing flickering when performing some types of updates
(e.g., recomputing Style2CSS). To workaround this, sometimes we force
animation callbacks to redraw ourselves at certain points.

This fixes issue #491 on Firefox
Merge pull request #496 from peitschie/ui-flicker

Reduce UI flicker when performing CSS updates
Do not display <text:bibliography-source/>
Merge pull request #500 from kossebau/hideTextBibliographySource

Do not display <text:bibliography-source/>
Don't crash if the requested range is outside the any document root

Fixes a crash when running the benchmark.
Merge pull request #497 from peitschie/benchmark-fix

Don't crash if the requested range is outside the any document root
Use a new ops.Canvas.getSizer instead of peeking
at the ancestry of the document root in SvgSelectionView.
Hide native selections only when virtual
selections are used.
Merge pull request #501 from adityab/native-selection-fallback

Re-enable selections for ODP and ODS documents
Use setStyle whenever selecting a new
style in the dialog.

This requires directly selecting a style
when cloning it, without waiting for onAdd.
Merge pull request #499 from adityab/pdialog

Load current style properties when opening dialog
Fix troublesome quotation of font-family name in CSS rule for embedded fonts
Change welcome.odt to have rich text in annotation and embed&use a font

Font is "Sonsie One" from http://www.google.com/fonts,
Licensed under SIL OPEN FONT LICENSE Version 1.1
http://scripts.sil.org/OFL
Merge pull request #502 from kossebau/fixFontEmbedding

Fix font embedding
Fix editor's welcome.odt: no more non-ODF elements, proper embedded font decl.
Merge pull request #510 from kossebau/makeWelcomeOdtValidated

Fix editor's welcome.odt: no more non-ODF elements, proper embedded font decl.
Revert OperationFactory interface changes made in a1f86ac

By specifically invoking a new when creating an operation instance
makes it quite difficult for external operation constructors, as there
is no easy way for external ops to share non-document state.

All WebODF ops don't have this issue as new functions can easily be
added to the OdtDocument interface to support the new requirements.
Merge pull request #464 from peitschie/opfactory-tweak

Revert OperationFactory interface changes made in a1f86ac
Only save style properties which have actually
been modified by the user in the dialog, upon
pressing "OK".