Constraint enablement preferences UI for the EMF Validation Framework.
Package Specification
This package implements the UI for enabling and disabling constraints in the
EMF Validation Framework.  It also displays to the user the critical details
of constraints:  name, evaluation mode, severity, and description.
The three major types in this package are:
   - {@link org.eclipse.emf.validation.ui.internal.preferences.ConstraintsPreferencePage}:
       The preference page implementation
- {@link org.eclipse.emf.validation.ui.internal.preferences.ICategoryTreeNode}:
       Defines the API for nodes in the category tree (left side of the
       preference page).  The nodes allow enablement and disablement of
       groups of constraints, in addition to a sensible organizational
       structure
- {@link org.eclipse.emf.validation.ui.internal.preferences.IConstraintNode}:
       Defines the API for items in the constraints list (right side of the
       preference page) for the current category selection.  Each constraint
       node can be individually enabled or disabled, unless it is in a mandatory
       category or it is forcibly disabled by a run-time exception
Other types in the package constitute primarily implementations of these
interfaces and utility methods.
@see org.eclipse.emf.validation.model