[Devel] Persist / State extension changes

[David Robillard]

Hi all,

Some minor issues have come up with the (still experimental) persist
extension.  In order to be efficient/useful for doing fast state things
in memory in one process, the host needs a way to request different
'style' of value - e.g. portable, serialized, POD, or fast and in-memory
but not portable.

I have added a flags parameter to save() and restore() to facilitate
this.  This also adds a bit of future proofing that was missing, since
other flags can be added if other similar scenarios crop up.

To avoid ugly binary breakage, I have put these changes into a new
"state" extension, which is here:

http://lv2plug.in/ns/ext/state

Comments welcome.

-dr

P.S. Note shiny new syntax highlighting in generated documentation