- before release of 0.4.0: extend gen.data function to include
  functionality used for the BiomCutoff paper.
  Also: remove names in lasso-based selection.

- extensibility: instead of a predefined set of functions, the user
  should be able to use a function of his/her own. This way we do not
  have to keep on adding new things

- add a BioMark-package man page

- parameter ntop should also possibly be a fraction, then to be
  interpreted as the fraction of variables to be included in the
  primary selection. Check whether this is not bigger than the
  fraction of variables to be left out, or probably half of that.
