#6 Add standard component for 'selected' like 'checked'

[Andrew Oliver]

option elements have a selected attribute which is boolean like 'checked'. However, setting it currently requires a workaround like using std:if with two versions of the option.

This ticket will add a new standard 'selected' component.

[Andrew Oliver]

The cleaner way to handle this is to use the existing html:bidir-value on the parent select element. Then there is no need to manipulate the selected attribute on options. For example:

  <select html:bidir-value='myProperty'>

binds the JavaBeans property 'myProperty' to the select. The value is fetched via getMyProperty() for rendering, and when the selected value changes, setMyProperty is called.