Clear storage and branch preserves B register (Van Snyder)
Merge Fixes from Bob Supnik's updates
SCP: Fix Set Command dispatching and HELP dev SET output

 - Fixed set MTAB dispatching to not dispatch to unit specific routines when only a device is specified in the command
 - Fixed HELP dev SET output to avoid displaying SET commands which aren't valid for SHOW only cases
sim_sock.c allow validation address to match various forms of literal localhost addresses.
README: Update to correct URL for windows binaries.  #70
PDP11/VAX: pdp11_hk Fix by Bob Supnik for issue #47

Revised error handling to command-response model
Revised interrupt logic to follow the hardware
Updated PDP11 and VAX780 documentation.
Compiler nits for void * assignments from Bob Supnik
I1401: Read TMK does not write GM+WM to memory from Bob Supnik
PDP11: Addition of the RS03/RS04 disk devices from Bob Supnik

Note that this is not the fully general Massbus implementation people were dreaming of. MB#1 is for RP/RM, MB#2 is for TU, and MB#3 is for RS.
I know that there were requests for four Massbus channels and multiple RP/RP subcontrollers, but if people want more disks, they can use the RQ.
PDP11: Added help to RK device
SCP: Added help display for units which can be enabled and disabled
PDP11: fixed auto configure for RL and HK devices
PDP11: fix RK device unit detection when some units are disabled.
VAX: Compiler warning cleanup
Merge branch 'master' of github.com:simh/simh