added class to extract a list of valid metadata from the toar database
added testscript for this class

added notebook to use this new class to extract data for all stations between 2000 and 2018.

excluded already processed year.

-changed from one large request to yearly requests
-changed waiting time for individual requests
-cleaned up

toar_rest_client:
-added function to alter the waiting intervals before checking for the results
-added indention to cache file
-worked on debug output
-

extraction of 19 years is no spilt into several requests covering one year each.

worked on README
- added syntax highlighting to code snippets
- reworked information on examples
- added some links and now hiding urls
- added tested OS

added some typing for return values in rest toar_rest_client
added flag to control debug output by toar_rest_client; Default: False

fiexed bug in produce data manyStations

split into usage of optional parameters and an example without a restriction, that will run for several days.

enabled execution with additional query parameters

added some error handling when using a cahced endpoint

under development

added comments to produce_data example