ENH: copy notebook scripts to examples folder, add notebooks to distribution

FIX: change exit()-calls to raise

Merge pull request #61 from wradlib/fix_ascale

Fix a scale, closes #60

DOC: add sweep_centroids bugfix to release_notes.rst

FIX: fix sweep_georef and derived tests

FIX: fix issue #60, `ascale` missing factor 2

Merge pull request #57 from kmuehlbauer/notebooks

Add notebooks 2

WIP: add nbsphinx_allow_directives to conf.py, use nbsphinx-fork until merged upstream

WIP: add recipes notebooks, remove recipe.rst, fix-doc references, fix notebooks

FIX: fix code bugs in notebooks

ENH: add wradlib_attenuation and wradlib_get_rainfall notebook, reference in docs, fix doc-references, remove now outdated rst- and example files

WIP: add wradlib_workflow.ipynb, remove tutorial_workflow.rst, fix doc-links

WIP: remove tutorial_reading_dx.rst

WIP: add wradlib_reading_dx.ipynb, remove tutorial_reading_dx.rst, fix doc-links

MIN: remove example files, which are already converted to notebooks

MIN: speed up zonal_stats_polar while increasing coverage

Merge branch 'master' into notebooks

WIP: fix filename issue (do not use colons), add rhi example file

Merge pull request #56 from kmuehlbauer/notebooks

WIP: add more notebooks

MIN: hide import cell in docs