Added "LegacyAssembly" property to "DSCoreNodesUI.DummyNode"
Updated path which was broken because of changes in Installed folder name.
Introduced "DummyNode.Nature" to differentiate Obsolete and Unresolved nodes
Renamed "CreateDummyNodeForFunction" to "CreateUnresolvedFunctionNode"
change to Dynamo07
Introduced "MigrationManager.CreateMissingNode" method, added test case
revert
revert
Redirected relevant callers to call "CreateMissingNode" instead
revert
Improved DummyNode to tell a Deprecated node from an Unresolved one
"Bad nodes" are now turned into "Dummy nodes" during load time
Few comments refering for DS Curve so cahnged that to Curve Geometry.

As we are removing DS from everywhere so comments needs to be updated.
Updated "MissingNode.png" with one that is designed in-house
remove the migration for string 0.6 to 0.7
Updated "Image.Stretch" to "Stretch.None" to avoid stretching
AssertValue from MirrorData in TestFramework

Fixes http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-2567
Removed "DynamoLoader.LoadSamplesMenu" because it's not used
Opening sample file from menu now asks user to save file and clear undo stack
Added new test case "CleanWorkbenchClearsUndoStack" for the fix