Called by the framework during form deserialization
to validate a form view. Default implementation validates each field
by calling 'validate'form-view-field'.

If this function succeeds validating the form it returns
true. Otherwise returns nil as the first value, and an association
list of fields and errors as the second value.

'object' - the object the form is being deserialized into.
'view' - form view object being deserialized.
'parsed-values' - an association list of field-info structures and
parsed values.