[Feature] Add Support to place an image in the QR-code's center

[oliveratgithub]

Could you add a possibility to insert a middle centered image, merged with the QR-code itself (for when downloading), like in this PR to the original library?

davidshimjs/qrcodejs#291

Note: if yes, it would be great to not only support base64 encoded PNGs (they seem to loose transparency), but actual unconverted PNGs, and/or SVGs :)