_  added MR kref for ref counting, so far we only use the refcount for
 creation / teardown but in the futur we will need to use it for all
usage of MR.

_ change the creation / teardowm sp it is comaptible with kref and also
rcu for destruction ( to be used with seqlock for search)

the full refcount usage will happen once all datastructure ( HMR - HPROC
and HSPACE ) have been moved to kref - rcu model
Merge branch 'blopeur-dev' into use-kref-for-hmr