WATM — Separate different conformance levels by Level numbers

In the current specification the different conformance options are separated
by version numbers; version 1.0 that does not include hand-off and version
2.o that supports hand-off.

This can be quite confusing and the confusion is likely to multiply in the
event that the whole specification is updated and receives new version
number.

My suggestion is to use similar technique as in CORBA security, where
different conformance levels are separated, not by version numbers, but by
Level numbers.

I suggest that we change "Version 1.0" to "Level 0" and "Version 2.0" to
"Level 1".

see above