Bug 7619 Use CRLF as default terminator

Bug 7619 Use CRLF as default terminator

Most units require or tolerate CRLF as the terminator
Using only \r causes many including 3M units to signal errors
due to delay this resets CRLF to be default but adds a single
constant variable and explanation so that if you have a
"strictly conforming" unit (the 'Baby' is the only I have encountered
you know where to make the change

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>