When looking for chars to indicate raw repl is active, look for the full
string of chars to improve reliability of entering raw repl correctly.
Previous to this patch there was the possibility that raw repl was
entered in a dirty state, where not all input chars from previous
invocation were drained.
In raw REPL ">" indicates the prompt. We originally read this character
upon entering the raw REPL, and after reading the last bit of the
output. This patch changes the logic so the ">" is read only just
before trying to send the next command. To make this work (and as an
added feature) the input buffer is now flushed upon entering raw REPL.
The main reason for this change is so that pyboard.py recognises the EOF
when sys.exit() is called on the pyboard. Ie, if you run pyboard.py
with a script that calls sys.exit(), then pyboard.py will exit after
the sys.exit() is called.
This makes pyboard.py much more useful for long running scripts. When
running a script via pyboard.py, it now waits until the script finishes,
with no timeout. CTRL-C can be used to break out of the waiting if
needed.
Improvements are:
2 ctrl-C's are now needed to truly kill running script on pyboard, so
make CDC interface allow multiple ctrl-C's through at once (ie sending
b'\x03\x03' to pyboard now counts as 2 ctrl-C's).
ctrl-C in friendly-repl can now stop multi-line input.
In raw-repl mode, use ctrl-D to indicate end of running script, and also
end of any error message. Thus, output of raw-repl is always at least 2
ctrl-D's and it's much easier to parse.
pyboard.py is now a bit faster, handles exceptions from pyboard better
(prints them and exits with exit code 1), prints out the pyboard output
while the script is running (instead of waiting till the end), and
allows to follow the output of a previous script when run with no
arguments.
