CorpusUtils#partitionCorpusByFileSize reads files in the given corpus base directory and its subdirectories
CorpusUtils#partitionCorpusByFileSize produces more uniform partitioning
fixed incorrect import in ReportingStatusCallbackListener
XmiCollectionReader is refactored to use XmiCollectionReaderBase & look up files in subdirectories
a small fix in XmiFileListReader
FSCasDirectory does more robust mapping docURI -> XMI file & FSCasDirectory looks up files in subdirectories