* TESTUPF: Move from internal/ to internal/test/unpackfilename
to be parallel with filepos
* IOCHAR: FILEPOS respects external format (#3)
* FILEPKG: EDITCALLERS speed up with new FILEPOS
* internal/test/filepos: Testing jig and cases for new FILEPOS
* EXTERNALFORMAT, IOCHAR: fix external-format glitches