Fixed handling or regular expression strings, so the regular expression functiuonality works, not just substring detection! Added special handling if the severity marker is "ignore". Unsuprisingly, it ignores that line.

Adjusted sf-run-analysis-raptor so that when preprocessing the files, STDERR is appended, but STDOUT is not.

Pre-emptive performance fix - avoid having to read the complete log file into memory at the same time before processing it.