bi-directional aggregation - guard output

[thezoggy]

With nfsen, doing list flows > bi-directional with outputs other than auto/line/long it fails due to unknown output mode 'bi###' unless its auto/line/long.

Figure there was no plans to add the other bi-output formats, so perhaps at:
https://github.com/phaag/nfsen/blob/main/html/process.php#L70

Have guard to only do -o bi$format if format matches line/long?
if ( $is_bidir && (in_array($format, array("line", "long") ) {

[phaag]

Well - bigline is not supported, however my recommendation would be to create all output formats of your choice in ndfump.conf. The guard may be possible, but at some point we should compile the available output formats from what is available and configured in nfdump.