course 7.x-1.6

Fixed:

#2491659: Add configuration to graded-based access to specify which item to use for evaluation.
#2472603: Default to private content when acl/content_access are present, and the node is new
#2488834: clone and reference node objects
#2484087: weights sometimes not saved correctly
#2482607: update resizeframe.js so it resizes on resize

Removed deprecated hook_course_enrollment_alter() hook in favor of hook_entity_op
Fixed an issue where an object that reports that it cannot be cloned ended up referenced
Fixed a fatal when using signup with no signup date.
Fixed an issue where signup users were accidentally re-enrolled if their enrollment was inactive.