Derive CanvasView from Dockable
Access to main menu items + switching active canvas + close button
Window titles
Close documents when DockDialog closed
Defeult DockBook for new opened canvases
Fix compilation issues on WIn32
Merge pull request #84 from blackwarthog/dockable-documents

Detachable CanvasView tabs
Fix bug #488 http://www.synfig.org/issues/thebuggenie/synfig/issues/498