white/black listing for filetypes and names

- add a whitelist for extensions based on the already-existing $known_extensions array in BaseScanner
- add a blacklist in two parts:  a list of banned extensions and a list of banned filename patterns
- each filename is checked during a scan and the following logic is applied:  If whitelisted, then no error.  If blacklisted, blocker.  If gray (neither white nor black) we have an unknown file extension, so produce a warning.
- this also fixes an bug that was preventing reporting of some errors via cli (due to missing line)