Inconsistency with bioRad in application of sd_vvp

[adokter]

Vol2bird sets bird densities to zero when there is a gap detected in the radial velocity field:

vol2bird/lib/libvol2bird.c

Lines 3888 to 3890 in 0eece2c

	// set bird density values to zero if hasGap:
	if (hasGap && birdDensity>0){
	alldata->profiles.profile[iLayer*alldata->profiles.nColsProfile + 12] = 0.0;

BioRad does not consider this gap, and simply divides eta by the cross section

Need to make these two consistent

[adokter]

Postprocessing efforts at UvA suggest that often you want to keep density when there is a gap, so therefore better to change vol2bird and keep bioRad as is

[adokter]

No longer setting birdDensity to zero when hasGap is True. Closed by commit 83106a8