- remove the service CvtSvc
- introduce a new module extjs containing a configurator class for each ExtJS component.
- introduce a new module converter containing helper function transforming web2py dal object into ExtJS configurator.
- deploy configurator in the rest of the code.
- define an xtype forl the App.Viewport class.
- Remove the widget class and transform the Spacer into a configurator.
- clean the navtree module. Helper function are replaced by configurator

 - Use the gluon.dal.Table and Field instead of tablename and fieldname
 - Rename cfgSvc as cvtSvc and all methods
 - break the foreign field service into a set of helper functions
 - break the setfield service into a set of helper functions
 - polish documentation and remove obsolete modules

- break backward compatibility through new naming /order of the model component (db, default, plugin, widget)
- Define one Node class and remove previous definition
- Add a configurator for single panel displaying url
- Modify the cfgSvc to give access to form and grid configuration remove the method get_configuration.
- Modify the appviewport to instanciate the widget from the configuration encapsulated in the leaf.

- Modify the cfgsvc.get_configuration to return None
- Modify the model to run a simple report
- Modify the appviewport to handle the case of a panel with an url
- Modify the controller reports/report_1 to run with the current
  database definition

navigation tree.

- Add new modules navtree and the class NodeBase and NodeDB
- Redesign the viewport_modifier and the cfgsvc.get_tree method
- Remove the obsolete method cfgsvs.get_tables
- Sort properly list according to the locale language

this work for all cases: a pure form or a form call from a grid.