Added support for Form Focus and Form Validate Events

This defines the focus and the validate events.

The focus events have the properties:

-modifier - is not supported on UNIX

-shift - true if the shift key is down during a particular event, false otherwise

-target - the field in question.

-targetName - The name of the JavaScript being executed.

It happens after we click the field and before we click out of it.

Okular uses Annotation:FocusIn to handle these type of actions.

For the field validate, we use the Okular::FocusOut, because it's executed after the user stops editing the field.

I left some defined properties on it, because they were mostly for ComboBoxes/ListBoxes