nimyara - libyara binding for Nim

[dmknght]

Nim binding for libyara4 - <https://github.com/dmknght/nimyara> Example of how 
to use API to scan files, directories: 
<https://github.com/dmknght/nimyara/blob/master/tests/sample_scan.nim> 
Documentation for Yara API: <https://yara.readthedocs.io/en/stable/capi.html> 
Example: scan zip file with Yara binding and nim zip 
(<https://github.com/nim-lang/zip)>: 
    
    
    proc do_unzip_scan*(scanner: ptr YR_SCANNER, path: string, user_data: ptr 
CallbackArgs) =
      # FIXME huge memory usage. Likely because of lib
      var zip: ZipArchive
      if not zip.open(path):
        echo "Failed to open file"
      else:
        for zipped_file in walkFiles(zip):
          # https://github.com/nim-lang/zip/blob/master/zip/zipfiles.nim#L142
          let
            extracted_name = getMD5(zipped_file)
            tmpFile = "/tmp/" & extracted_name
          if cast[ptr CallbackArgs](user_data).scanningPath == "":
            cast[ptr CallbackArgs](user_data).scanningPath = 
expandFilename(path) & "//" & zipped_file
          else:
            cast[ptr CallbackArgs](user_data).scanningPath = cast[ptr 
CallbackArgs](user_data).scanningPath & "//" & zipped_file
          zip.extractFile(zipped_file, tmpFile)
          scanFile(scanner, tmpFile, user_data)
          removeFile(tmpFile)
        
        zip.close()
    
    
    Run