View tree UI improvements
Add magnifying glass to inspect views on hover
View tree: add options to  show components and all views

Also added the ability to inspect a view's DOM element by clicking on its template

Done with @twokul
Show views and components in preview layer
Update tests to new features and fix bug with private view properties
Drop objects when destroyed
Better filtering of views when highlighting on hover
Accounts for view not having an element when highlighting

Fixes #65
Add name column to view tree and hide virtual views
Merge pull request #63 from tildeio/view-tree

View tree improvements