MFC bectl(8)/libbe(3): r337663-337664,337667,337697-337699,337800,337805,

MFC bectl(8)/libbe(3): r337663-337664,337667,337697-337699,337800,337805,
337915-337918,337921,337924,337947,337993-337995,338221-338222,338303,
338417,339047,339972,339994,340334,340507-340508,340592-340594,
340635-340636,340722-340723,340974,342466,342849,342903,342911,343335,
343543,343977,343993-343994,344034,344067,344084,345302,345769,
345845-345846,345848,346082

There are simply too many small changes to enumerate; in summary:

bectl(8)/libbe(3) has been introduced from current state in -CURRENT and
added to the stable/11 rescue build. bectl(8) is a tool for managing ZFS
boot environments, largely inspired by beadm. It includes features such as
being able to jail a boot environment or easily mount it for modification.

Relnotes:	probably