Also, removed unnecessary debug print

serialSyncChannel ticker is parameterized

See merge request !3

Also, removed an unused shared, probably leftover from old code, from when addBackgroundTask was used

Empty the output channel after sending

See merge request !2

Previously, it wasn't empting the output channel unless new messages were received. This caused multiple messages to be sent until some message was received.

Fixing termios flags on macOS

See merge request !1

Accordinng to http://kirste.userpage.fu-berlin.de/chemnet/use/info/libc/libc_12.html:
"CLOCAL
If this bit is set, it indicates that the terminal is connected "locally" and that the modem status lines (such as carrier detect) should be ignored.
On many systems if this bit is not set and you call open without the O_NONBLOCK flag set, open blocks until a modem connection is established."

Apparently (by testing and from a tip online), macOS is one of those systems.