Editor / improve attribute support

[fxp]

Currently, GeoNetwork does not load information for attributes from the schema. When an attribute exists in the XML metadata record, the simpleElement template is used and display a simple text input (except for @codeListValue). But some attributes have enumeration defined by ISO.

Changes:

• Add support for enumeration in attribute (eg. gml:timeInterval/@unit, @gco:nilReason, gml:begin/@indeterminatePosition). Most of them are in the gml schema.
• SchemaLoader load simpleType and memberTypes in union
• Attributes are displayed in a div below the field in edit mode (see screenshot) - div content is visible if one of the attribute is defined, collapsed if not.
• Add an option to edit gco:nilReason attribute in editor (turn off by default) in order to set other values (ie. not only 'missing' added automatically by update-fixed-info).
• Use duration widget for gml:duration
• Add curstom template for gml:timeInterval in view mode (value is timeInterval * @factor / @radix with @unit)
• Fix partial @indeterminatePosition support

Also in the patch:

• use textarea for more description elements
• measureDescription and evaluationMethodDescription may be multilingual
• fix support for multiple graphicOverview (using url)

Example for gml:timeInterval in metadocument:

<gml:timeInterval unit="month" radix="3">
  1
  <geonet:element ref="333" parent="332" uuid="gml:timeInterval_867f4f59-4c09-46a1-81f2-c7a162c36b35" min="1" max="1" />
  <geonet:attribute name="unit">
    <geonet:text value="year" />
    <geonet:text value="month" />
    <geonet:text value="day" />
    <geonet:text value="hour" />
    <geonet:text value="minute" />
    <geonet:text value="second" />
  </geonet:attribute>
  <geonet:attribute name="radix" del="true" />
  <geonet:attribute name="factor" add="true" />
</gml:timeInterval>

[fxp]

r6971