Improve javascript archetype for form handling and validation

Hello,

After looking carefully at form.js and core.js. There are problems with the skeleton concerning form validation :

• There is no way to override or intercept a form submit event if the form is submitted asynchronously, same for refresh or cancel ....
  this is very much needed if you want a function to be notified when one of this event happens
  WETHER by tapestry.form.onsubmit("myForm", myFunction) OR tapestry.connect("myForm", "onsubmit", myFunction)

• There is no standard way to append a validation message to the stack of validation messages created from the form profile.
  One should be able to call tapestry.invalid_field('The field blah is invalid', isMissing ) And this should be appended to normal validation

• Validation profiles are rather not clear, complicated and considered as instable in the dojo tree, all the validation should not depend only on this mechanism...

• tapestry.connect assumes you connect a function in the tapestry namespace !? that's wrong, it should be :
  For 3 args : search for the function in the tapestry namespace and global namespace
  For 4 args : search for the function in the given namespace

• validation using tapestry should not impose its method to show JS validation messages... Actually it is a a dialog widget from dojo. But it should be made simple to override that with your own presentation function :
  ex: tapestry.form.summarizeErrors(form, messages)

Numa