Internal function which changes some elements of output ENVI files:
file extension is set to .dat if .envi (in case of files created by 'writeRaster`) is found, and the header is edited properly,
and band names are set in the header file (in particular, SR band names include wavelengths and names like NIR, SWIR; other products shows the product name as band name);
SCL headers include information about class names and colours.
fix_envi_format(infiles)
A vector of input filenames, in the sen2r naming convention (safe_shortname) and ENVI format.
NULL (the function is called for its side effects)