ZNE channels and BNG

[ispingos]

Trying to use BNG with components already tagged as ZNE does not work because the BNG.calc function works exclusively with channels Z12.

Explicitly stating the system with the -c flag does not seem to work on this. This does not permit validation of (supposedly) oriented stations.

I'm attaching a batch script (and the related StDB file) that reproduces the issue (perm_station_issue.zip).

Will also post a proposed fix (albeit a bit rough) in a new PR.