Rearrange DBG_REG debug logging to reflect driver programatic access to the device registers.  Created a DBG_RGC to display internal changes to the registers.

Changed the behavior of device wen register changes happen to delay 20 instructions before acting on changed register state.  This is useful/necessary since some driver code writes some registers with the same value twice to be sure that the device notices the write.  We must male sure we don't try to act on the same write events more than once.
Reverting simh.sln file accidentally included in the merge commit
Merge latest pdp11_dmc with the length prefixed packet headers into DDCMP conversion work.

Added more DMR11 functionality used by the VMS driver
  - Fixed processing of DMC microcode step logic to trigger on all of the correct conditions
  - Fixed DMC11/DMR11 SEL0 register behavior when clearing RDI to also clear the input command bits.
Added initial 22 bit DMV11 addressing support
Minor sim_debug line termination fix if a sim_debug call produces an empty string (i.e. no output).
Added simulator version (and git commit id) to the debug message issued when a debug session is enabled.
Fixed Data Packet CRC injection and revised DDCMP debug output to have the detail flag control only the display of raw hex packet output, packet header info is always output
Added debug flags to optionally display packet contents in DDCMP debug output
Add support to construct DDCMP maintenance mode packets
Rewrite of pdp11_dmc to support DDCMP