Flems in docs (#2348) [skip ci]

* Initial addition of flems - fixes #526

* Fix leftover ```js code blocks

* Add DOCTYPE

* Fix edge & IE11

* Don't show console

* Change orientation on mobile

* Use mithril@next for playground link

* Improve loading and structure

* Fix header alignment in IE

* Don't rotate logo

* Fix conflicts

* Allow `js` tags

* Fix code block query

* Fix Routing section and flems

* Fix firefox

* Improve flems styling

* Improve copy

* Fix data -> body in m.request sample

* Add flems in docs usage description

scripts/lint-docs.js

@@ -106,7 +106,6 @@ class LintRenderer extends marked.Renderer {
 			}
 		}
 		this._ensureCodeIsHighlightable()
-		this._ensureCodeHasConsistentTag()
 		this._ensureCodeIsSyntaticallyValid()
 		this._ensureCommentStyle()
 	}
@@ -135,12 +134,6 @@ class LintRenderer extends marked.Renderer {
 		}
 	}
 
-	_ensureCodeHasConsistentTag() {
-		if (this._lang === "js") {
-			this._emit("JS code block has wrong language tag", this._block())
-		}
-	}
-
 	_ensureCodeIsSyntaticallyValid() {
 		if (!this.lang || !(/^js$|^javascript$/).test(this._lang)) return
 		if (this._error != null) {