Improve export conversion script

[Deinonychus71]

Ideally, any set of IDSP/LOPUS/BRSTM/NUS3AUDIO should be exported to a single, consistent format. In case of LOPUS, it should be allowed to select a bitrate.

GIVEN a song with $toneId {ToneId}, $conversionFormat lopus and $bitrate {bitrate} IF input = IDSP, do a frequency check, if frequency isn't 48khz, do a sample conversion to 48khz, convert to lopus using $bitrate, then convert to nus3audio with $toneId IF input = IDSP, do a frequency check, if frequency is, convert to lopus using $bitrate, then convert to nus3audio with $toneId IF input = Lopus, do a header check, if header isn't right, convert to Lopus with Namco header + $bitrate, then convert to nus3audio with $toneId IF input = Lopus, do a header check, if header is right and target $bitrate is lower than current bitrate, convert to Lopus with Namco header + $bitrate, then convert to nus3audio with $toneId IF input = Lopus, do a header check, if header is right and target $bitrate is equal or higher than current bitrate, convert to nus3audio with $toneId IF input = nus3audio, if internal format is IDSP, extract IDSP with ??, then use IDSP rules IF input = nus3audio, if internal format is LOPUS, but toneId needs to be updated, use ?? to update the ToneId, then use LOPUS rules IF input = nus3audio, if internal format is LOPUS, and toneId matches filename, use LOPUS rules IF input = BRSTM, convert to IDSP, then use IDSP rules