Change includes stdlib.h and stdio.h to cstdlib and cstdio to avoid C
macro definitions
Fix ffmpeg export for OSX
OSX: Fix synfigstudio startup fail if previous run location is missing
OSX build: Copy launch script when synfigstudio compilation is done

That way we can test synfigstudio without building an app package.
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
Update walk.sifz example
Fix dock_info
Add TODO comment about dock_info workaround
Linux build: Fix library cleanup
Merge remote-tracking branch 'ivan/dockable-documents' into morevna

* ivan/dockable-documents:
  Defeult DockBook for new opened canvases
  Close documents when DockDialog closed
  Window titles
  Access to main menu items + switching active canvas + close button
  Derive CanvasView from Dockable
Merge remote-tracking branch 'origin/0.64.1' into morevna

* origin/0.64.1:
  Linux build: Fix library cleanup
  Add TODO comment about dock_info workaround
  Fix dock_info
  Update walk.sifz example
  OSX build: Copy launch script when synfigstudio compilation is done
  OSX: Fix synfigstudio startup fail if previous run location is missing
  Fix ffmpeg export for OSX
  Change includes stdlib.h and stdio.h to cstdlib and cstdio to avoid C macro definitions