bugfix in densities over time
removal of erroneous test data
removal of erroneous test data
recreated test data
update density over time test code
start implementation of violin plots
energy transition test data added
violin plot added as an option
small work around in test data
violin plot continued implementation and testing

violin plot appears to be working for the major plot types.

density over time still needs work
refractoring of plotting code
log option added back in for density plots
small change in call signature of helper function
small changes to how violin plots are shown

inspired by seaborn same small visual changes to violin plot