Change several input parameters

[Gabriel-p]

• Make the lower mass limit a fixed parameter
  The mass range used to sample the IMF has a large impact on the total mass estimated, particularly the lowest mass. Make these input parameters with default values: 0.08, 150

• Add a flag to turn completeness on/off
  With Gaia data many times we can assume total completeness. This would speed up the process of generating synthetic clusters significantly. Related Enhance completeness algorithm (crowding effect, empirical function) #301

• Remove 'max_mag'
  Use all stars that are selected/given as members

• Remove 'N_interp'
  Related to Artifact in the interpolation of binaries #508, simply use 1500 as default

• Change 'min_mass_ratio' to 0.5 or implement another 'q' distribution?