idstools.rule fails to parse new snort3 rules

[nilsrennebarth]

The parser does not support snort3 service rules, file rules and file identification rules.

• Service rules have a 2 word header action service, where action is the normal snort action and service is the name of any application layer service, e.g. http, smtp, imap, ... They avoid port based detection of e.g. http and are applied to any packet that has been identified as belonging to the given service.
• File rules have a 2 word header like service rules, but instead of a service they have the file keyword. They are applied whenever a file upload or download has been detected.
• File identification rules have the header file_id and do not generate alerts but identify files based on the contents of that file and then define a file type that can be used in subsequent rules.

The actual rule part looks like a normal snort rule in all cases.