Fix some problems with class and className

src/IconButton.tsx

@@ -2,13 +2,12 @@ import { h, JSX } from "preact";
 export default function IconButton({
    children,
    className,
+   class: c,
    ...props
 }: JSX.HTMLAttributes<HTMLButtonElement>) {
    return (
       <button
-         className={
-            "ht-btn ht-btn-icon " + (className || "") + (props.class || "")
-         }
+         className={"ht-btn ht-btn-icon " + (className || "") + (c || "")}
          {...props}
       >
          {children}