Segtools

* dropped official python 2 support
* all tools are now supported on python 3
* updated build system and removed legacy installation scripts
* added support for wheel distributions
* latest docs now available on segtools.readthedocs.org
* updated existing test cases
* added runtime checks for genomedata in segtools-nucleotide-frequency and segtools-signal-distribution
* added CITATION.cff for aiding in citation

* add support for rpy2 version 3

* segtools-overlap: added compatibility with python 3

* removed external dependencies when reading version information during setup

* segtools-length-distribution: set same y-label for length-distribution and segment-sizes plots
* segtools-gmtk-parameters: added compatibility with python 3
* segtools-length-distribution: added compatibility with python 3
* segtools-aggregation: added compatibility with python 3
* segtools-feature-distance: added compatibility with python 3
* segtools-preprocess: added compatibility with python 3

* remove ez_setup from installation
* remove setup information for data files requiring distutils and MANIFEST.in