gwb-grid: rework help text, add version info

[tjhei]

FYI: @mibillen

[gassmoeller]

Looks much cleaner to me.

[MFraters]

Looks great, thanks! One small request for an addition, otherwise good to go.

[MFraters]

while we are at it, can you also add the git hash?

[tjhei]

done

[MFraters]

Thanks!

[tjhei]

I will need to update some test output, I think.

[codecov]

Codecov Report

Attention: 7 lines in your changes are missing coverage. Please review.

Comparison is base (1ae31ff) 93.49% compared to head (f5a2f34) 93.54%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #550      +/-   ##
==========================================
+ Coverage   93.49%   93.54%   +0.05%     
==========================================
  Files          92       92              
  Lines        6346     6340       -6     
==========================================
- Hits         5933     5931       -2     
+ Misses        413      409       -4     

Files	Coverage Δ
source/gwb-grid/main.cc	46.29% <0.00%> (+0.11%)	⬆️

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1ae31ff...f5a2f34. Read the comment docs.

[github-actions]

Benchmark	Main	Feature	Difference (99.9% CI)
Slab interpolation simple none	1.019 ± 0.006 (s=467)	1.021 ± 0.005 (s=418)	+0.1% .. +0.3%
Slab interpolation curved simple none	1.025 ± 0.004 (s=432)	1.026 ± 0.004 (s=448)	-0.0% .. +0.2%
Spherical slab interpolation simple none	1.262 ± 0.004 (s=368)	1.261 ± 0.003 (s=348)	-0.1% .. +0.0%
Slab interpolation simple curved CMS	1.095 ± 0.005 (s=394)	1.095 ± 0.004 (s=430)	-0.1% .. +0.1%
Spherical slab interpolation simple CMS	1.856 ± 0.005 (s=236)	1.856 ± 0.005 (s=251)	-0.1% .. +0.1%
Spherical fault interpolation simple none	1.269 ± 0.003 (s=354)	1.273 ± 0.005 (s=357)	+0.2% .. +0.3%
Cartesian min max surface	2.364 ± 0.022 (s=197)	2.365 ± 0.023 (s=186)	-0.3% .. +0.4%
Spherical min max surface	7.395 ± 0.038 (s=65)	7.393 ± 0.014 (s=59)	-0.3% .. +0.2%