fltrator : init at 2.3

fltrator : added patch to made fltrator-landscape use the correct data directory.

fltrator : corrected an error with meta

fltrator : enhancement based on srhb suggestion

fltrator : add .desktop

fltrator : enanced the build file, based on suggestion of jtojnar & srhb

fltrator : use nativeBuildInput rather that buildInputs. suggested by jtojnar

fltrator : desktop file is now pointing to the specific binary, and has icon.

fltrator : deleted the manual unpack phase