Update jaudiotagger with a fix that removes some System.out calls

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
FlacTagConverter: newer flac files can have DISCTOTAL fields

Originally a discnumber (like 1/2) was in the DISCNUMBER field.
In newer flac files these can be split in DISCNUMBER and DISCTOTAL
fields.

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: build the projects with Gradle (v5)

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
gradle: add a (temporary) script to fully exercise the build

I keep having to look up all the targets...

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
findbugs: more effort and more reports

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>