Add import/export/paste model functionality to editModels.js
Add ModelTree::getModelAt
Merge branch 'master' of git://github.com/highfidelity/hifi into 19783

Conflicts:
	interface/src/scripting/WindowScriptingInterface.cpp
	interface/src/scripting/WindowScriptingInterface.h
Add pasteModels
Add LocalModelsOverlay
Add SendModelsOperation
Implement pasteModels in Clipboard
Add localmodels overlay type
Update and add localModels overlay to editModels.js import/export
Update LocalModelOverlay to work prorperly with translations
Rename buttons in editModels.js
Add ModelTree::findModelsInCube
Fix export models not cancelling correctly
Update exportModels implementation
Update clipboard call to exportModels to not scale to tree size
Fix bug with ModelItemProperties

When copying from a ModelItem the properties should be considered
changed
Add more complete error handling for import/export models
Cleanup editModels.js
Remove TODO comment
Cleaup several qDebug calls and commented lines