Allow to close and reopen on OML4R session
Allow to close and reopen on OML4R session

* Add some channel cleanup code
* Allow to unfreeze MP

This make the following code work.

	OML4R::init(ARGV, opts)
	MP.inject 1
	OML4R::close

	OML4R::init(ARGV, opts)
	MP.inject 2
	OML4R::close

Signed-off-by: Olivier Mehani <9858fe98d2c7f5f35e0d2a08f134cfc58afd42d3@nicta.com.au>

mytestbed/oml,lees0414/EUproject,mytestbed/oml,alco90/soml,mytestbed/oml,alco90/soml,alco90/soml,alco90/soml,mytestbed/oml,lees0414/EUproject,mytestbed/oml,lees0414/EUproject,lees0414/EUproject,lees0414/EUproject,alco90/soml