fix a bug when not using -s/--split, output file was opened in write mode, so it would get overwritten multiple times, leaving only data in it from the last plugin
better formatting of output stats, not in addition to just 'required' for a subrecord, non-required subrecords display how many records have the subrecord.
fix -p/--plugin command line switch
dumps combined stats either to the end of the combined file,  or a separate txt file when using -s/--split
added progress bar to loading files