* Add Base64 library to utils * Fix typo on Base64 padding * Added documentation for Base64 and references from ERC1155 and ERC721 * Updated Changelog * Fix typo in utilities doc * use mstore8 to improve memory accesses * use shorter strings with encodePacked * do not use using-for syntax, for clarity Co-authored-by: Hadrien Croubois <hadrien.croubois@gmail.com> Co-authored-by: Francisco Giordano <frangio.1@gmail.com>