More SAX2 proposals ...

[David Brownell <david-b@pacbell.net>]

I'm sending a second batch of proposals along.
Again, all of these are backwards-compatible,
and most are extensions (SAX-ext)

In this batch:

    - SAX-ext #4: feature/property discovery
    - SAX-ext #5: DefaultHandler2
    - SAX-ext #6: parser versioning
    - SAX core #1: class loading
    - SAX core #2: factories

The previous batch was:

    - SAX-ext #1: standalone flag
    - SAX-ext #2: Attributes.isSpecified
    - SAX-ext #3: entity encoding and version

The same meta-questions apply, and I've used
the same answers:  version-style evolution for
class/interface names uses numeric suffixes,
and the optional "extensions" stay decoupled
from the optional "helper" classes.

As before, I'll see followups to both lists, but
please follow up only to one of them.

- Dave