Rename makeUserHidden to Key.makeSystem
MRTask2 vs MRTask
remove auto-convert dregs

and Mem Cleaner for VA
Remove various races from TestKeySnapshot

Stall-till-cluster.  Block on remove from one test before starting next.
Bring RPC & Autobuffer fixes back from h2o-dev

autobuffer close would free a TCP channel a 2nd time, if called a 2nd
time from an exception handler path.
Vec keys all use the vec-key generator
GLMGridProgress file collision

StableAPI complains about the now-removed GLM1 pytjhon api.  There is
also a GLM2 Grid api, not tested in StableAPI
Remove apparent false-positive from DL spirals

very slightly weaken error bounds
Turn on the rest of the MRThrow tests