test_binary_sampling, first commit

- tests multiple algorithms for creating binary samples,
  including sampling from full imf and sampling secondaries
  from a restricted IMF with M2 < M1.

- plots mass distribution of primaries-only, secondaries-only,
  primaries+secondaries, primaries AND secondaries, and
  binary mass ratio distributions for each type of sampling.

- [to do:] flat secondary distribution has not been tested yet.
plot_dN_dM

- modified to calculate samples using rejection sampling, which
  is easier to modify when testing various binary sampling algorithms,
  albeit slower.
myanalysis

- small changes
main.py: minor change only
lf_parsec_darth

compares LF of Dartmouth and PARSEC isochrones for same set of
IMF parameters.
plot_eda and plot_eda_ferr

- plot output best-fit parameters as a function of number of stars
  in isochrone, limiting magnitude, photometric errors.