Copied only necessary decoding functions from the lodepng opensource.
See: https://lodev.org/lodepng/
additional changes:
- disabled crc for the optimal size.
- converted the format bgr -> rgb for our png example.
Still we don't have a concrete idea for the image formats,
We should fix the converting methods between bgra <-> rgba.
@Issue: https://github.com/Samsung/thorvg/issues/594