Add missing svn:keywords property.
Add mkimg_write() which combines lseek(2) and write(2) and uses
sector granularity for both offset and length. Have all schemes
use mkimg_write() instead of mkimg_seek() followed by write(2).

Now that schemes don't use lseek(2) nor write(2) directly, it's
easier to support output formats other than raw disks.
dd(1) uses gettimeofday(2) to compute the throughput statistics.  However,
gettimeofday returns the system clock, which may jump forward or back,
especially if NTP is in use.  If the time jumps backwards, then dd will see
negative elapsed time, round it up to 1usec, and print an absurdly fast
transfer rate.

The solution is to use clock_gettime(2) with CLOCK_MONOTONIC_PRECISE as the
clock_id.  That clock advances steadily, regardless of changes to the system
clock.

Reviewed by:	delphij
MFC after:	3 days
Sponsored by:	Spectra Logic
Change the device name for mpr(4) from /dev/mpr_N to /dev/mprN.

This is more consistent with the existing mps(4) behavior.

Reviewed by:	Steve McConnell <stephen.mcconnell@avagotech.com>
MFC after:	3 days