better support for using checksummed file timestamps as a higher resolution file timestamp
better support for using checksummed file timestamps as a higher resolution file timestamp

jigneshvasoya/ruffus,pombreda/ruffus,kmonsoor/ruffus,bunbun/ruffus,d4g33z/ruffus,magosil86/ruffus,pombreda/ruffus,aeron15/ruffus