Plankton Toolbox 1.3.0 released

Plankton Toolbox 1.3.0 was released on August 29th 2018. The new release includes a major update of the counting module. In addition the HELCOM-PEG 2018 biovolume list is used. The list of potentially harmful taxa has been updated accorrding to the IOC-UNESCO Taxonomic Reference List of Harmful Micro Algae. Also many under the hood changes have been made, e.g. a move from Python 2 to Python 3.