added WCS support
added TimeSeriesDataSource
allows to use multiple source per TSD

# Conflicts:
#	timeseriesviewer/dateparser.py
#	timeseriesviewer/utils.py

avoids QgsMapCanvas() calls without any parent = None, which caused crashes on macOS

fixed import of ENVI spectral libraries

main.py vector layers are added to QgsProject.instance() map layer store (that we can still use the QgsMapLayerComboBox)
__init__.py removed dummy statememnt from __version__
removed Qt. calls

refactoring
added timeseriesviewertesting and moved tests to