overall, this makes parsing of FLIRT .pat files more robust. motivated by the work in https://github.com/fireeye/capa/issues/435.
adds:
- FLIRT: pat: line comments (extension of format, enables license headers)
- FLIRT: pat: parse tail bytes
- FLIRT: pat: handle large functions (greater than u16::MAX. this contradicts existing documentation of the FLIRT format!)