Remove ViewWest from client

The ComponentList isn't shown.
Add ComponentCell class

The ComponentCell defines the menus that list components and actions
that can be performed on a component. It replaces the ModelCell class
in ModelTree.
Move ViewInputFilesPanel to "ui.widgets" package
Deprecate ComponentList, DragCell and ModelCell

They're no longer needed. Remove them later.
Remove ClickHandler for ModelTree

The click event is handled by the ComponentCell.
Strip drag-and-drop event handling from ModelTree

Drag-and-drop functionality is obsoleted by the ComponentCell.
Replace ModelCell with ComponentCell on initialization of ModelTree
Add enclosingTreeItem member to ComponentCell

As with the ModelCell, the ComponentCell needs to know where it is in
the ModelTree.
Add port-counting methods to ComponentJSO

Also deprecate goofy #getPortsProvided and #getPortsUsed in favor of
#getProvidesPorts and #getUsesPorts.
Add new components to ModelTree

Still need to handle:

- "linked" components
- actions on the components
- filtering "provides" components

Deprecated methods that added ModelCells to the ModelTree.
Experiment with CSS for ModelTree
Show only components that match a component's open uses port

Also initialize the ModelTree when WMT starts. Update the list of
available components after they've been read.
Add icons to ComponentCell menus
Add worker ComponentCell#addComponentMenuItem
Set up framework for performing actions on components
Change ViewCenter to ViewWest because because
Implement the "Get info" action in the ComponentCell
Implement the "Show parameters" action in the ComponentCell
Add "portId" and "componentId" members to ComponentCell
ComponentCell actions classes accept the ComponentCell reference

…instead of the underlying component id. Useful because the
ComponentCell has both the component id and the port id.