[INTERNALS]
De-anonymized the callbacks and handlers in Test::Harness, mostly
so I can profile better.Checks _is_header() only if _is_line() fails first. No point
in checking every line of the input for something that can only
occur once.Inline the _detailize() function, which was getting called once
per line of input. Reduced execution time about 5-7%.Removed unnecessary temporary variables in Test::Harness::Straps
and in Test::Harness::Iterator.