Avoid losing already set arguments on identify.

When we exec identify, we don't want to lose the options set for the other commands that will come after identify.

This should fix autoOrient (calls orientation, which in turn execs identify) acting up as in #99
added; handle Buffer as source
Merge pull request #106 from danmilon/buffer-as-source

added; handle Buffer as source
ws
ocd

this codebase is crappy
docs;
added; gm.compare support
update README
release 1.7.0
Fixed autoOrient to work with all types of exif orientations.
test using compare as well
fix faulty test
gitignore
fixed; magnify support
tests; cmd line args
tests; fix magnify test on imagemagick
tests; npm test runs unit only
remove incorrect/broken dissolve method

closes #85
.travis
tests; fix tests on absolute paths