message: vertexcodec: Fix pgram trace for starting vertices
  Generally several vertices at the beginning of the block have useful
  pgram prediction data but are forced to use delta prediction atm since
  the referenced vertices are from the previous block.
diff: @@ -68,9 +68,16 @@ static unsigned char* encodeVertexBlock(unsigned char* data, const unsigned char
  unsigned char pc = prediction[i] >> 0;
  assert(pa > 0 && pb > 0 && pc > 0);
  + if (pa <= i && pb <= i && pc <= i)
  + {
  printf("pgram %d %d %d", pa, pb, pc);
  }
  else
  + {
  + printf("pdelta");
  + }
  + }
  + else
  {
  printf("delta");
  }
  