modify gitignore. don't track .png files
Clean data loading in behav Rmd and rename.

Improve transparency in data loading portion of behavioral Rmd file.
Plain text and comments are added to track decisions made for handling
the data.

Some error checking has been added to verify that indeed the number of
hits, misses, crs, fas, and unsures maps onto the number of valid old
and new trials. There are also more steps where the markdown will print
out what the current state of the data frames. More error checking
should be added to ensure that the dataset is coming in the right form.
Add investigation of rt. Style clean up.

Lots more to do to recreate bamm plots, but it seems clear that they
were wrong, and what's actually happening is an interaction between
phase and memory class on rt (for rec and fam).