refresh item when dd options change
[composer] Make sure general atlas properties are imported before importing items from xml, so that items can be aware of atlas context while they are being created
Disable rotation spinbox when data defined rotation is enabled
Data defined must reprepare expression if expression changes
[composer] Refresh data defined properties when composer refresh button is clicked
[composer] Fix hang with enabling atlas on a map with a point coverage layer while preview is active
[composer] Data defined rotation rotates around item center. Also update bounds of composition when item rotation changes (since that may affect the bounds).