Handle large diffs in non-color mode
Don't print help in "--log"

The user explicitly asked for a log and thus knows what he is doing.
Gracefully handle keyboard interrupt

Previously, a keyboard interrupt would result in a corrupted terminal.
This would manifest when doing "cdiff --log" on somewhat large
repositories.
Merge pull request #11 from myint/sigint

Handle keyboard interrupt gracefully
pypi now has https
- Fixed incorrect yield on diff missing eof
- Fixed a bug in diff format probe
- Handle keyboard interrupt and large diffs in non-color mode
- Code clean up