handle station type

See merge request toar/machinelearningtools!16

new method check_station_meta to compare meta data of locally stored file (implemented: station_type, station_network). /close #23

/close #14

See merge request toar/machinelearningtools!15

introduced module "modules" to collect all working steps (like experiment setup, pre-processing) in separate folder

some paths are still not updated and will cause errors (WIP)

restructured experiment setup, therefore deactivated some functionality in run.py and modules.py (tests fill probably fail now!)

See merge request toar/machinelearningtools!14

can look in superior scopes too, can list all names available in data store, return either just object name or (name, scope, value) in search scope, /close #24

first implementation of data store with 2 different designs but same functionality, not decided yet which representation is more suitable