unit test for making `step` respect linestyle as a kwarg
Changed `step` to append the user specified `linestyle` onto the
`linestyle` that is passed to `plot` instead of silently ignoring it.
pep8 fixes
variable name tweaks for readability
fixed random text insertion
fixed small issues with png test output, probably related to changes made in c48afe4b36112c58a45621c58c4a9f6f767f82c5
added CHANGELOG entry for this feature.
add flushing of stdout to update on key event

Doing this as a demo for UC Berkeley Practical Neuroimaging class on
contributing to open source while getting your work done
Merge pull request #1802 from tacaswell/step_linestyle

Step linestyle
Merge pull request #1848 from ivanov/keypress-stdout-flush

add flushing of stdout to update on key event