[PATCH 0 of 3] hgext/extdiff patches

[Brad Schick]

3 extdiff patches refactored as requested by Benoit. These changes make
extdiff a bit more useful directly and also easier for other extensions 
to reuse.

3 files changed, 96 insertions(+), 73 deletions(-)
hgext/extdiff.py       |  143 +++++++++++++++++++++++++++---------------------
tests/test-extdiff     |   12 +++-
tests/test-extdiff.out |   14 +---