Move to UUID based scheme from ElementID scheme

And update all the classes and tests except for AbstractAnalysisDsiplay
Add a migration for Levels drop down.
More consistent naming on drop down types.
MAGN-2233. Face selection always needs to reset internal selected element.
MAGN-2124. Make null parameter values export as empty string.
MAGN-2408. Re-point migration methods for element selections to ModelELementSelection.
Fix two viz manager tests.
Add shutdown logic to UI tests and fix inheritance issues.
Refactor startup and shutdown methods on UI tests to share same test setup methods.
Add some garbage collection to tests.
Add logic to ignore guides that are all on single values

To support the way in which the compiler is current emitting rep guides,
IList marshalling failure demo

Demo that the marshalling is different for List<double> and IList<double>

For the first promotion happens successfully, for the later it doesn't.
Test contains nodes that we're not delivering in 070
Verification of empty list replication behaviour
Replace the error message with a sensible one and comment out the code for easier analysis
Merge pull request #1347 from DynamoDS/ChocoButter-2Become1-ElementIdentity

Choco butter 2 become1 element identity
Language backing test for single -> replicated -> single

Attempting to repro: http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-2452
Merge branch 'ChocoButter-2Become1' into Breadcrumbs