Use richer data types for the View DSL

[pcdavid]

In #1426 we introduced the InterpretedExpression (resp. DomainType) EDataTypes in view.ecore to identify string attributes which are expected to contain AQL expressions (resp. domain type names). This is useful to provide richer details view with widgets more precisely chosen/configured than what the generic choices would make.

There are other kinds of attributes which are currently encoded as raw EString or EInt but could benefit from being more precise:

• Color (EString): could be represented with a color picker when we get support for that.
• Dimension or Length: currently any string, but if we (the widget) knew it is supposed to represent a CSS length we could provide some client side validation.
• Feature(Name) (EString): this is similar to DomainType. It is supposed to reference the name of a meta-model element feature (for example in CreateInstance.referenceName) and could benefit from some completion/validation support with a more precise definition than "a string".

Note that adding these data types would be useful even just in terms of documentation if we do not exploit them immediatly.