Fixed name of data file name
Competitive binding fit
Moved layout_140429... to sub directory

Planning to add a series of PySB models, which will be easier to do in
separate files within a single directory.
Original XLS data from Justin for 4/29/14

Plan is to parse this data in so that I can get all of the information
from the timecourses and replicates.
Basic parsing of 140429 FRET data from XLS
Fit individual FRET curves to exp funcs

Also plot the (rather strange) dependence of the starting fluorescence
value on the amount of WT cBid (more likely, on the position of the well
in the dilution series).
Added a todo list
Refactored BG and FA avg calculations into funcs
Made the bg/fa avg funcs more self-contained

Anticipating splitting the data/XLS parsing code from the
plotting/analysis.
Separate analysis from XLS data parsing
Wrote func to calc FRET from endpoint values
Put the curve fitting code in own func

Also wrapped the calculate_fret function with another function so that
it can be used to simply get the data without passing underlying
arguments or generating plots.
Refactored simple fits

Now the plots are with errorbars; data comes from calculate_fret, rather
than from the .csv file.
Initial implementation of hill func fit by MCMC
Wrote prior func
Some minor changes before some bigger refactoring

Am going to change to using the real competitive binding equation.
Moved hill_func_mcmc to comp_bind_mcmc
Basic competitive binding, MCMC

Actually can get fits from this. However, I believe this method relies
on the approximation that Lf ~= L0 (i.e., there's a very small amount of
the receptor so that the ligand is not appreciable depleted). Would be
better to have a version in which this assumption is not made.
Two site competition binding model

Taken from:

Wang, Zhi-Xin, Jiang, Ruo-Fan, "A novel two-site binding equation
presented in terms of the total ligand concentration." FEBS Letters 392
(1996) 245-249.
Renamed comp_bind

Am planning to create a third script with the exact equation for
competitive binding, which will obsolete this one.