• Add $json->encode_to($fh, $data, [$type]) to stream encoded JSON directly
  to a filehandle instead of building the whole result in memory
  (GH #250, requested by yairlenga. designed 2016 in GH #58).
  Internally flushes a bounded 8k chunk buffer as it fills, keeping
  peak memory bounded for large data structures.
  
• Encoder performance improvements suggested in GH #237 (17dec):
  
  • Large-integer encoding now uses a 100-digit lookup table instead of
    snprintf, roughly 2x faster for integers outside the existing
    branchless small-integer fast path (|value| > 59000).
    
  • encode_str now bulk-copies runs of consecutive bytes that need no
    escaping instead of a need()+store per byte, notably faster for
    strings with few or no characters to escape.