Show cause of error when opening drag-&-dropped files fails.
Plumb the error code back from the FILE_OPEN command, and display errors
in the existing bullet list error dialog used by DragAndDrop.
Add unit test to verify that FILE_OPEN command now returns error code when
it fails.

Also, cleanup: group image-related tests into a single describe() instead
of a separate one per it().
Merge remote-tracking branch 'origin/master' into pflynn/dragdrop-errors

And clean up blank-line spacing in DocumentCommandHandlers-test
Add "showCursorWhenSelecting" pref
fix Issue #8953- add Extension Manager support for localized extension package metadata.
update localization example for reference
update localization readme for reference
as requested per code review
changes per code review
Merge remote-tracking branch 'origin/master' into bchin/localize-package-metadata
Rebased project manager
Changes based on review comments
Fix merge error (WORKING_SET_VIEW) and update working set test.

The DOM structure has changed a little in the tree.
Fix problem with DragAndDrop test.

This was very hard to track down because our promises and event handlers swallowed
an exception thrown in FileTreeViewModel.
Fix problem with InlineEditorProviders-test.

The project files cache was not being cleared on every file system change, as it had
been previously. Also removed duplicate projectClose event.
- fixed typo in FileViewController.WORKINGSET_VIEW which caused errors opening files from working set
Fix context menu behavior when you right click from one node to another.
Merge branch 'ProjectManager' of https://github.com/adobe/brackets into ProjectManager
Revert "- fixed typo in FileViewController.WORKINGSET_VIEW which caused errors opening files from working set"

This reverts commit 83b95c402b5ccfa1ac679bf05908545e86d742ca.
Another couple of WORKINGSET_VIEW cleanups