Project tree view and creation (#203)

* Implement creating and importing new projects

* Add downloading a zip of a project

* Project validation (WIP)

* Add project side panel, remove project pages

* Project file saving

* Add file tree actions to rename and delete

* Fix file creation auto focus

* Add button to save file from menu

* Add project creation

* Fix specificity on version switcher button

* Update default version to 1.19

* List project files by type, remember project and delete project

src/app/components/Modal.tsx

@@ -0,0 +1,38 @@
+import { useCallback, useEffect } from 'preact/hooks'
+import type { JSXInternal } from 'preact/src/jsx'
+import { LOSE_FOCUS } from '../hooks'
+
+const MODALS_KEY = 'data-modals'
+
+interface Props extends JSXInternal.HTMLAttributes<HTMLDivElement> {
+	onDismiss: () => void,
+}
+export function Modal(props: Props) {
+	useEffect(() => {
+		addCurrentModals(1)
+		window.addEventListener('click', props.onDismiss)
+		return () => {
+			addCurrentModals(-1)
+			window.removeEventListener('click', props.onDismiss)
+		}
+	})
+
+	const onClick = useCallback((e: MouseEvent) => {
+		e.stopPropagation()
+		e.target?.dispatchEvent(new Event(LOSE_FOCUS, { bubbles: true }))
+	}, [])
+
+	return <div {...props} class={`modal ${props.class ?? ''}`} onClick={onClick}>
+		{props.children}
+	</div>
+}
+
+function addCurrentModals(diff: number) {
+	const currentModals = parseInt(document.body.getAttribute(MODALS_KEY) ?? '0')
+	const newModals = currentModals + diff
+	if (newModals <= 0) {
+		document.body.removeAttribute(MODALS_KEY)
+	} else {
+		document.body.setAttribute(MODALS_KEY, newModals.toFixed())
+	}
+}