Include the modified nodes into the reachable list

1. The modified nodes are always going to be executed. They should
always be added to the reachable guid list
2. Modified the testcases to reflect this
Merge branch 'master' of https://github.com/DynamoDS/Dynamo into defectfix
Revert minor change
Add new DynamoSlider class.
Moved DynamoSlider to CoreNodesUI.
Move serialization shared logic into base class.
Hand-pick changes to slider classes and base class.
Remove dead IBlockingModel interface.
Fix two tests which referenced old Dynamo slider class.
Remove the old DynamoSlider class.
Remove two dead event handlers.
Rename to Number Slider and add search terms.
Rename double slider and add search terms.
Delete Dynamo Sample Custom Nodes from repo
Remove WindowsBase dependency.

Threading namespace is no longer needed. Remove WindowsBase reference
and cleanup unused using statements in several locations.
Visual tweaks to expander and slider.
Merge pull request #3371 from junmendoza/defectfix

Include the modified nodes into the list of reachable node list
Use DispatcherUtils.DoEvents() to ensure the Dispatcher has emptied it's queue before doing UI assertions
Merge pull request #3412 from pboyer/killpkgs

Delete Dynamo Sample Custom Nodes from repo
changed class to static
Merge pull request #3430 from aparajit-pratap/changeStatic

Made CompilerUtils a static class