don't use Blockly at all on editCode levels

Previously, editCode levels still kept a div around called Blockly, loaded the blockly-core vendor.js, and injected Blockly into the page (while keeping it hidden).

I cleaned this up now so BlocklyApps.usingBlockly is the opposite of BlocklyApps.editCode and we only do Blockly things inside BlocklyApps.usingBlockly.
These flags contain redundant state, and their names are not obviously mutually exclusive. How about "usingDroplet" instead of "editCode"? If you don't want to rename them, please add a comment stating they are mutually exclusive.