This patch makes the following changes:
 - Remove (non-deprecated) method
   DescriptorParser#parseDescriptors(byte[], String) which we clearly
   forgot to deprecate earlier and which we shouldn't support in the
   future. It returns a List (rather than Iterable) and throws
   DescriptorParseException rather than include UnparseableDescriptor
   in the result. Might deserve an extra notice in the change log.
 - Put back a few lines `this.unrecognizedLines.add(line);` which got
   lost in previous commits.
 - Remove `failUnrecognizedDescriptorLines` parameters everywhere.
 - Remove more obsolete code from DescriptorReaderImpl.
 - Remove now obsolete attribute oldExitListEntries from ExitListImpl.