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