Initial version of phybema and first test data set

differences to Phybema as described in the B.Sc.-thesis of Birgitta P"auker:
  1) use a python implementation of neighor joining. This saves
     system call since the neighbor-joining algorithm is called
     as a python function
  2) conversion of output format is not necessary anymore. For
     all distance estimators we require that they output a matrix in
     phylip-format, either as a triangle or full matrix and with or
     without zero-values on the main diagonal