Updated minimal version of py_tools_ds (fixes issue #29 (Exception: dlopen: cannot load any more object with static TLS)).

Merge dev branch into master.

Closes #22

See merge request !14

Interpolation methods for spectral or spatial interpolation during dead pixel correction are now separately configurable.

Revised spatial interpolation within dead pixel correction and added tests. Added pandas to conda requirements.

Revised interp_nodata_along_axis_2d (speeds up spectral interpolation by factor 40-50). Adedd numpy-indexed to dependencies.

Added config parameter 'enable_ac' (L2A contains TOARef instead). Revised file sizes in L2A XML file. Added ortho information to L2A XML. Bugfixes.

Added first version of L2A metadata to XML conversion. Further developed output writers. Revised paths getters.

Added Geometry_Transformer_3D (fixes issue #22). Fix for passing a negative viewing zenith angle to SICOR.