1. Special mode to search in error logs: if SEARCH_RANGE is not set,
   the file is considered an error log and the search is performed
   since the last CURRENT_TEST: line
2. Number of matches is printed too. "FOUND 5 /foo/ in bar".
   Use greedy .* at the end of the pattern if number of matches
   isn't stable. If nothing is found it's still "NOT FOUND",
   not "FOUND 0".
3. SEARCH_ABORT specifies the prefix of the output.
   Can be "NOT FOUND" or "FOUND" as before,
   but also "FOUND 5 " if needed.