pyInterface: clean up config file

general clean up of the config file and the package/_config.py module.
Delete config entries "massBinDirectoryNamePattern" and
"dataAmplitudeDirectoryName". Delete amplitude category and put folders for key
and amplitude files into general section. Create category "other" and put all
weight related stuff, as well as amplitude subdirectory names in there.
Create a function that manages all the directory handling. The function checks
if the config file has the option and assigns a default if the option does not
exist. It also expands environment variables and checks if an absolute path was
given. If it recognizes a relative path it returns the path relative to the
position of the config file (and NOT relative to the current path).
Thanks to sensible defaults the config file works in theory without giving any
of the general options. The initialize method creates directories (for data, key
and amplitude files) if they do not exist yet.
pyInterface: add amplitudeBenchmark.py

add a script that runs a benchmark test if the result of the calcAmplitudes
script is consistent with the result of the script on a benchmark machine. Also
add a script that compares 2 amplitude files. The script will save 2 histograms
for the differences between the files, one for the real and one for the
imaginary parts.
pyInterface: add integralBenchmark.py

add a script that runs a benchmark test if the result of calcIntegrals script
is consistent with the result of the script on a benchmark machine. This
test ensures the precision of calcIntegrals on different machines.