Added cumulated transform sequence, to make it easier to implement object coordinate systems.
Save accumulated transform sequence in assembly instances.
Merge remote-tracking branch 'upstream/master' into OSL_objectspace
Merge remote-tracking branch 'upstream/master' into OSL_objectspace
Merge branch 'master' into OSL_objectspace
Split computation of accumulated transforms for assemble instances.
Object space transforms working. Updated OSL scenes with refs.
Merge pull request #415 from est77/OSL_objectspace

Store the accumulated transform sequence from worldspace in assembly instances.
Merge pull request #425 from fewo/master

Add a pixel inspector tool
several improvements around the project file watching functionality.

- fixed error message when enabling the project file watcher on a built-in project.
- the state of the file watching toggle is now saved to the settings.
- reordered methods in renderer::MainWindow.
small code tweaks and cleanups.
Merge pull request #427 from fewo/master

- Add tile ordering option in appleseed.studio under render setting/syst...
fixed issues with new tile ordering settings.
Fixed object space PR comments.
Merge pull request #428 from est77/master

Fixed object space PR comments.
Merge pull request #429 from fewo/master

Pixel inspector tooltip hiding / add new icons.
immediately show the pixel inspector when 'i' is pressed.

tweaked the text of the pixel inspector tooltip and refactored the code.
using spaces instead of zeroes to pad pixel coordinates in the info label.
tweaked tooltip text.
many improvements around the project file watcher functionality.

- the Toggle File Watcher toolbar button and corresponding menu items are now checkable.
- moved the corresponding menu item to the File menu.