pyInterface: start cleaning up pyInterface/package.

Start cleaning up the rootpwa python package by moving quite a number of files
dealing with amplitude calculation to a newly created legacy script directory.
There is no replacement at the moment, but this will be added over the course
of the next few commits.
pyInterface: Add new amplitude submodule.

Add a new amplitude submodule to the python package which only contains one
function at the moment: it calculates the amplitude for an input file and a
keyfile and saves that to an output file. With this, it should be possible to
write a new calcAmplitudes.py quite comfortably.
pyInterface: Clean up the python package some more.

Move more files to the legacyScript directory and clean up some of the
__init__.py files. Also change the core submodule from a directory to a .py
file.
pyInterface: convertEvtToTree

new converter python script for converting *.evt files to *.root files.
pyInterface: convertEvtToTree.py

New version using eventFileWriter.
pyInterface: convertEvtToRoot.py

Converter uses EventFileWriter now.
convertEvtToTree.py Exception handling
pyInterface/genPseudoData.py -> eventFileWriter
Implement eventFileWriter into genPseudoData.
changed decayTopology to fix genPseudoData.py

Since the implementation of the eventFileWriter into genPseudoData.py the
arguments of decayTopology's methods (which took ROOT Objects) were
impractical. Change the Python wrapper as well as the source files to
reflect the new handling. The changes in genPseudoData are minor.
pyInterface: genpw.py -> eventFileWriter

Implemented eventFileWriter into genpw.py. Still unsure if Comgeant output parts
should remain (only commented out for now).