Revert "removed fp output file"

This reverts commit 5e7836a5e776d094dc23a984ab33f2821ecf7348.
Merge branch 'master' of https://github.com/lell/genetics
code to simulate coalescent with recombination
wrap recombinator code + add command line

also: holdit will hold out its input in
the test/train paradigm.
Merge branch 'master' of https://github.com/lell/genetics