some helper funcs for plotutils
add MarginalHistScatter class
add_legends method for MarginalHistScatter
clean up imports
add three_prime, five_prime, TSS, and TTS methods to ResultsTable
more import cleanup
support for hist_kwargs in genes_to_highlight
kwarg setup and default handling
rm padding code
use marginal histograms
add rug plots
_updatecopy can override
add comments
nicer default for rug plot
gmin/gmax for one-to-one line
mv color_converter
cleaner plotting code

general kwargs and hist_kwargs are now prepended to genes_to_highlight,
de-duping some parts of the code
fix kwarg updating
minor
add limits property to MarginalHistScatter