working on stim pipeline

[JesseLivezey]

PR is intended to do a few things

• Get some of the data scanner functionality working better with new paths
• Get TDT mark/wav working
• some code cleanup
• some testing cleanup

generate_nwb.py runs for R56_B13 although I haven't inspected the nwb file.

Closes #14 Closes #35

[jihyunbak]

Thanks for this @JesseLivezey !

See also: PR #40, which depends on PR #39 (39 is ready for review)