Important unimplemented features in current device-mapper implementation

* implement dm_dev_event_ioctl and dm_target_msg_ioctl functions

* write more targets mirror, stripe.

* snapshot target, there is some code in repository already

* enable dynamically loadable targets

			Pain in the sky tasks

* implement multipath target for network attached storage devices.

* Cluster lvm extension, NetBSD needs Distributed Lock Manager for this.

* write GPL free libdevmapper and lvm2tools.