Progenetix API for Biosamples

After some hiatus we have re-started the work on the Progenetix API. The updated version now has functions for accessing sample data using simple filters.

Examples are e.g. the retrieval of sample data in JSON or tabular format, or the counting of samples matching a given parameter.

In principle, the API supports all sample query options from Beacon+, using an appropriate query string.

More information and example links can be found in the code documentation.

@mbaudis 2020-01-22