added error reporting

Change-Id: Iddfe49a0733e5e574d01aae79c608a51d6c59fce
preventing grouped callbacks from causing immediate server requests

Change-Id: I8ee3939e858581bdd704bdf5fdebac31ff58c589
Avoiding unnecessary RPCs in isBranch() and hasChildBranches()

Change-Id: Ib50d3d6b06761a0b40f5a941f248fb23f1e1b707
DynamicColumnEditor improvements:
 - when hierarchy updates, finds and selects active column if not
previously found.
 - respects user category navigation when hierarchy updates after active
column was found.
 - selects active column when active parent category is clicked again.
Attribute selector now clears title when tool is disposed and unlinks
when the panel is closed.
CustomTree.scrollToAndSelectMatchingItem() now accepts an item parameter
and makes sure equivalent items not appearing in list do not get
deselected by Flex ListBase.

Change-Id: If5fe3df778d16fc033fa89267fc906c3a6bcc63f