v0.0.15
added session support for multiple download nodes
replaced thredds catalog usage
revised grid mask logic
fixed missing progress for skipped chunks
changed error behaviour to quit on first exception
parallel downloads support
fixed 'string indices must be integers' issues
added support for progress monitoring via de-progress-api
added download cache support and optional clip to geometry cordex mask feature
provides optional filtering for space, time and variables
cordex mask border issue fixed
added HEESIL licence
fixed hadgem calendar issues
initial version