pyInterface: improve fileManager

change a lot of different aspects of the fileManager:
1) initialize by a config file. Add keyfile and amplitude file path to config
file.
2) open keyfiles and link their wave name to the file name in a keyFiles
dictionary.
3) handle bins only by binID internally.
4) implement amplitude paths. Works only without subdirectory (when the file
per directory limit is not reached) for now.
5) lots of minor bugfixes.
pyInterface: change config __init__ to initialize method

change __init__ method of config class to an initialize method, so we can
return True/False to indicate whether initialization succeeded or failed. Hence
we can have proper exception handling and don't have to use sys.exit(1) if
exceptions do happen. Change files affected by this update accordingly. Also
implement some checks to see if the key/amplitude directory is a valid
directory.