Render geophysical fields encoded in GRIB edition 2 using OpenGL

 This is the headless executable, based on EGL.
 Display GRIB2 fields with OpenGL. Raster, contour, vector, colorbar, mapscale,
 coastlines, borders. Lat/lon, lambert, gaussian grid. GLFW backend for
 interactive display, EGL backend for batch processing without X11 display.
 Perl/Tk interface.
 Tested on :
  - VGA compatible controller: Intel Corporation Xeon E3-1200 v3/4th Gen Core
 Processor Integrated Graphics Controller (rev 06)
  - VGA compatible controller: Intel Corporation HD Graphics 530 (rev 06)
  - VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Wani
 [Radeon R5/R6/R7 Graphics] (rev c8)
  - 3D controller: NVIDIA Corporation GV100GL [Tesla V100S PCIe 32GB] (rev a1)