Prep main_eda to test salpeter,chabrier,kroupa

- added if statements one for each option : salpeter, chabrier, kroupa

- for each option, one parameter (param_in_arr) is varied. for chabrier
  it is mc, for kroupa it is alpha1.

- imftype_in specifies input IMF assumed

- imftype_out specifies fitting IMF used. Currently set = to imftype_in,
  to modify this later, will need to modify param_out_arr to sample
  the wanted values for the param associated with that fit imftype,
  and will also have to modify the write to file to include BOTH
  input and output imftype.

- write to file: eda_salpeter, eda_chabrier, and eda_kroupa.dat
  will contain record of EDA for each imftype.