As it was in the real world, especially with dialup ports, it is possible
for an emulator AMLC line to get blocked by stray flow control characters.
The blocked port may appear dead to the next user to connect, if they are
not "serial savvy" enough to try sending an XON character.
A large number of vulnerability scanners have found and have been hitting
the public emulators, injecting HTTP transactions or worse into the AMLC
ports and often locking all of them daily.
This workaround injects an XON (DC1, 0221) and a line kill character as
extracted from the DEFKIL field in FIGCOM, into the AMLC line when a new
connection is received.
There is a -dolineclear command line switch to enable the behavior.
Deconflict some values of instruction count with some of the
other tracing options by making it require a leading # before
the integer count.
Add/fix support for tracing execution within a designated segno.
Announce to the trace file that tracing is initialized.
