test/field_minus.js, test/field_plus.js, test/procedures.js files copied from https://github.com/google/blockly-samples/tree/master/plugins/block-plus-minus and modified
test/blocks/ files copied from blockly source code (https://github.com/google/blockly) and modified
error icon in the web comes from https://www.flaticon.com/premium-icon/cancel_1008927?term=cancel&page=1&position=12&page=1&position=12&related_id=1008927&origin=tag
ukandrewc_Ace-Scrollbars/ is downloaded version of https://github.com/ukandrewc/Ace-Scrollbars