[MERGE] integrated EOL conversion support

[Stephen J. Turnbull]

Ian Clatworthy writes:

 > Thinking out loud, I wonder whether "windows" would be a better
 > choice than "dos"? I'm probably showing my age by using the latter.

One advantage to "dos" is that the definition won't change because of
a sneeze in Redmond. ;-)

But since "yes, we do cross-platform-including-Windows [as right as it
can be done]" is what you really mean (anybody have a DJGPP
environment supporting Python and bzr on DOS? maybe I should ask DJ),
probably that's the appropriate value here.