Merge pull request #1 from vallard1/master

junk_image works now.
Make batch use of junk_image efficient.
fixed bug in junk_image feature
np.copy array in subtract_drift
cleanup for simplicity
split() and stack() replace split_by_probe()
split() and stack() work
subtract_drift seems to be behaving now
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
updated split, stack in API
Merge remote-tracking branch 'upstream/master'
removed cast_probes from API
Merge remote-tracking branch 'upstream/master'
remove cast_probes
split_branches renamed branches
handled default value for msd_interval more cleanly
defined function is_smear to filter out unrealistic trajectories
Merge pull request #2 from vallard1/master

junk_image fixed
added is_smear to API