message: gltfpack: Add -vpi option to match current default
  Right now specifying -vpi does nothing compared to the default options,
  but it might become useful if we decide to change the default to -vpf
diff: @@ -1197,8 +1197,14 @@ int main(int argc, char** argv)
  {
  settings.col_bits = clamp(atoi(argv[++i]), 1, 16);
  }
  + else if (strcmp(arg, "-vpi") == 0)
  + {
  + settings.pos_float = false;
  + settings.pos_normalized = false;
  + }
  else if (strcmp(arg, "-vpn") == 0)
  {
  + settings.pos_float = false;
  settings.pos_normalized = true;
  }
  else if (strcmp(arg, "-vpf") == 0)
  @@ -1438,8 +1444,10 @@ int main(int argc, char** argv)
  fprintf(stderr, "\t-vt N: use N-bit quantization for texture coordinates (default: 12; N should be between 1 and 16)\n");
  fprintf(stderr, "\t-vn N: use N-bit quantization for normals and tangents (default: 8; N should be between 1 and 16)\n");
  fprintf(stderr, "\t-vc N: use N-bit quantization for colors (default: 8; N should be between 1 and 16)\n");
  - fprintf(stderr, "\t-vpn: use normalized attributes for positions instead of using integers\n");
  - fprintf(stderr, "\t-vpf: use floating point attributes for positions instead of using integers\n");
  + fprintf(stderr, "\nVertex positions:\n");
  + fprintf(stderr, "\t-vpi: use integer attributes for positions (default)\n");
  + fprintf(stderr, "\t-vpn: use normalized attributes for positions\n");
  + fprintf(stderr, "\t-vpf: use floating point attributes for positions\n");
  fprintf(stderr, "\nAnimations:\n");
  fprintf(stderr, "\t-at N: use N-bit quantization for translations (default: 16; N should be between 1 and 24)\n");
  fprintf(stderr, "\t-ar N: use N-bit quantization for rotations (default: 12; N should be between 4 and 16)\n");
  