Maintaining collapsed state during reload

[StanleyGoldman]

Note: This branch targets enhancements/branches-view-rollup #464

Adding functionality to maintain the collapsed folder state during the reload of items.

• Replaced fields with a dictionary object that will survive past a domain reload
• On loading items, before clearing that dictionary, we check it for the state of folders to use while populating items

Depends on:

• Tree view control for displaying data performantly. #151
• BranchesView Cleanup #468

[drguthals]

Looks good!