FeaturePanel_CustomForm - new widget

[adube]

Have a FeaturePanel widget used by the EditFeature widgets that loads an external script that builds a user-specific script.

The script should receive the resource id, feature id and formpanel id in order to work properly and build custom stuff depending on these parameters. Commit and Cancel actions must be triggered from the script elements.

[adube]

r970, featuring :

• new !FeaturePanel_CustomForm widget
• support in both XML and PGSQLMapContext configs
• documentation
• 2 samples, one per config type
• custom script that manages the "gmap popplace" resource coming from sample configs

Since the content of this widget is generated from an external script, it doesn't require i18n. That part should be managed by the script too.

possible improvements

• have options to manage the window options (this could also be managed by the custom script)

The task is completed. If more features should be added to this widget, we'll open a new ticket.