Coverity 1005133: fix unlikely case where malformed pcre statement in rule would lead to null-deref.
Coverity 1005134: fix minor memory leak on flowvar rule setup errors.
flowvar: cleanup keyword argument parsing. Should also address Coverity 400655.
file: make fileext, filename and filemagic use the same rule parsing function as others. This has as a side effect that we enforce doubly qouted values now.
Remove obsolete DetectParseContentString function, it has been replaced by DetectContentDataParse
Remove filemagic debug statement
Update DetectContentDataParse to reflect the actual data types content uses.