Rename the writeSequenceStarted variable to writeStarted

Conflicts:
	src/serialport/qserialport_win.cpp

Change-Id: I786879a485e78e3637d8cb474f86e3bd406bd237
Reviewed-by: Denis Shienkov <denis.shienkov@gmail.com>
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>