ranghetti/sen2r: Version 0.3.3

This is an improvement of version 0.3.2, with several fixes and improvements.

• Add internal logging (argument log of function sen2r())
• New function s2_dop() to know the Dates Of Passage over orbits
• Cloud mask can now be smoothed and buffered, both using sen2r() and the GUI
• Add apihub parameter in sen2r() and in the GUI: It is now possible to specify a custom apihub.txt file for specific executions (i.e. for scheduled processes).

• Minor edits in GUI
• Parallelise functions and manage errors
• Create load_binpaths() (#87: Create a function to load paths of external executables and adapt other functions to use it.
• Implement search for ingestion date
• Split names_missing into names_cloudcovered and names_missing
• Add some burn indices and update spectral indices from IDB
• Change some function names (s2_getMetadata -> safe_getMetadata; s2_shortname -> safe_shortname; fs2nc_getElements -> sen2r_getElements)

• Ignore baseline in computing required SAFE names
• Fix #82 (Now BOA and TOA uses GTiff intermediate files instead of VRT (gdal_calc failed using vrt as input, computing only the first band))
• Uniform some default argument values
• Various fixes