[MERGE REQUEST] bzr mv fix, and windows compatability fixes

[Ollie Rutherfurd]

Hi Martin,

Please consider merging the following revisions from: 
http://www.rutherfurd.net/bzr.orutherfurd/

1179: changed diff help example to -r1..2 from deprecated -r1:2
1178: fixed \r\n -> \n conversion in branch._check_format
1177: disable urlgrabber on win32, since it converts / -> \
1176: changed assert path.startswith('./') -> '.'+os.sep in merge.py
1175: replaced os.spawnvp with subprocess.call in msgeditor.py
1174: os.name == 'windows' -> 'nt', check for %EDITOR% on win32
1173: fixed bzr mv filename newfilename, re-enabled test_mv_modes

It would be great if these*, or equivlent changes, could be included 
before 0.0.7, so bzr works on windows (it may work on cygwin without 
them, I don't know).

* 1173 and 1179 aren't windows-specific.

Thanks,
-Ollie

PS - the changes above are the only differences from the current bzr.dev.