Now skip radii are defined for each height, in the drunkdict
cutting_session now can handle NaN values via bottleneck
Added new MCMC-based fitting code: MCtrane. It's legit.

Also a few changes to Coltrane and Salty2 in light of MCtrane, mostly just
squelching print statments.
Removed a lot of old, commented-out code from Coltrane
MCtrane is becoming more generalizable.

Still needs some lines to plot the traces