Puzzle: Make toBuffer for png/gif/jpeg to return Buffer or Uint8Array
Puzzle: Make toBuffer for png/gif/jpeg to return Buffer or Uint8Array

I tried to implement png/gif/jpeg routine to return buffer with node-canvas,
but I couldn't because canvas returns empty data.
I want to do it for future release, but I stop trying it for next release.

sabo2/pzprjs,sabo2/pzprjs