#80 add test pixel functions
#80 in nansat tests export to GTiff; export2thredss only not in conda environment
#80 add gdal_data and proj4 libs to travis.yml
#80 add --yes to conda installation
#80 travis.yml: move GDAL_DATA to install
#80 test_nansat, test_domain: use Agg backend of matplotlib
#80 test_nansat, test_domain: switch to Agg in each test
Merge branch 'issue91-test-pixel-functions' into develop