Fixes to:

 1) retain the buffered/unbuffered line specific details across save/restore
 2) retain modem control outgoing bits (CTS and DTR) accross line resets which may occur due to carrier/connection loss.
 3) change the behavior which sends  the prior contents of the transmit buffer on a line reconnect to only happen for buffered telnet lines.
 4) avoid crash in SHOW MULTIPLEXER output when only specific lines have been attached instead of
Addition of DUP11 simulation to all Unibus simulators (PDP11, PDP10, and all Unibus VAXen)
Added makefile support for the DUP11 device
Added logic to act on the state and transitions of the RCVEN bit of the receiver CSR.
Fixed CRC implementation, CRC state bit presentation and added register declarations
Fix packet transmit overrun behaviors which caused DECnet circuit failures.
Added rate limit support (SET DUPn SPEED=bps).
LP20 emulation was overwriting existing files

When an LP20 is attached to an existing file, the file is opened in
update mode.  Since the initial file position is zero, any existing
output is over-written.  This is not intuitive.

This edit makes the LP20 seek to EOF on attach.

N.B. Other devices may have cousin issues.
Add set serial to KS cpu

With multiple instances, error logging gets confusing when every CPU has
the same serial number.

This makes the CPU serial number settable.  If not set, the old defaults
apply.
Revert "Add set serial to KS cpu"

This reverts commit 611b7632c993006c5e4bd1d0fe3516cd3f6f4de4.
Add set cpu serial for KS

Allow CPU serial number to be set for KS cpus.

With multiple instances running about, this prevents a lot of confusion,
especially in the error logs.
Change some tabs to spaces
Add initial sharable DDCMP support
Cleaned up readme documentation to avoid potential confusion when initially setting up a windows build environment.
Changed some spaces and indentations
Merge remote-tracking branch 'github/master'
Fix for Unibus word DMA from Rob Jarratt
Added support to the Remote Console facility to close a remote console session on EOF
Merge branch 'master' of github.com:simh/simh
Cleanup DUP11 implementation and refactor for shared use by another device (KMC11).