Add Aztec 2D barcodes

[mjohndus]

Please note about the code:
Original code by @z38/metzli, rewritten by @bozhinov and adapted to tc-lib-barcode by @mjohndus.

[CLAassistant]

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[nicolaasuni]

Thank you for your contribution, it was inspirational.
Because of license and some technical issues, I instead implemented from scratch the AZTEC encoder via #79.