More compiler suggested cleanups
Use generic message routine for sim_accept_conn and sim_read_sock and don't emit a message if a read fails due to ECONNRESET (this is expected).
Add line number to line specific debug message output.
Change 8-bit characters to printable form.
Added per line Modem Control capabilities to TMXR
Added help info to asynchronous timer device
Added sim_getnames_sock to get a printable form of the endpoints of a socket
Added stability to virtual null modem connections by consuming all incoming per line connections until a good one (or none) is found.

Extended debugging to describe the socket endpoints when connections are established.
Extended XMT and RCV debugging to include the line number in debug messages.
Added randomization to the checking for success of outgoing connections and the arrival of incoming connections
Fixed DZ bug which referenced the wrong dz device when the number of DZ multiplexers configured was not a power of 2 (i.e.3, 5, 7, etc.)
Fix for Issue #53 for DC, DL, and VH multiplexer devices
Added a -E switch to the SHOW DEVICE/SHOW CONFIG/SHOW FEATURES command to only display Enabled devices
Added new tmxr_line_attach_string API to return the attach string specific to a a particular multiplexer line.

Added parsing logic to allow tcp port and connect strings to end in either ";notelnet" or ";telnet" as desired to specifically describe a port setup.
Fixed bug in single line multiplexer attach which returned failed status when it should not have if a tcp connect destination was specified.
Relaxed parsing rules to allow a single line multiplexer to have a listen port specified at either the line level or the mux level.
Added hex debug output for tcp session data on non-telnet line debug
Merge branch 'master' into BlinkenLights
Merge branch 'BlinkenLights' of https://github.com/jguillaumes/simh into BlinkenLights