Enabling target ED-value precomputation

Changed getopt to argparse in order to improve the commandline parsing.
IntaRNA commandLineArguments can now be added at the end of the python call and will be parsed correctly.
Changed calls.py script in order to allow the precomputation of target ED-values, that can then be used in further calls to improve the runtime.
Minor fixes to comments.
Updated README.md .

BackofenLab / IntaRNA-benchmark