all: rename the gioui.org/ui module to gioui.org

The "ui" is redundant and stutters.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/doc.go

@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+/*
+Package app provides a platform-independent interface to operating system
+functionality for running graphical user interfaces.
+
+Windows
+
+Create a new Window by calling NewWindow. On mobile platforms or when Gio
+is embedded in another project, NewWindow merely connects with a previously
+created window.
+
+A Window is run by receiving events from its Events channel. The most
+important event is UpdateEvent that prompts an update of the window
+contents and state.
+
+For example:
+
+	import "gioui.org/ui"
+
+	w := app.NewWindow()
+	for e := range w.Events() {
+		if e, ok := e.(app.UpdateEvent); ok {
+			ops.Reset()
+			// Add operations to ops.
+			...
+			// Completely replace the window contents and state.
+			w.Update(ops)
+		}
+	}
+
+A program must keep receiving events from the event channel until
+DestroyEvent is received.
+
+Main
+
+The Main function must be called from a programs main function, to hand over
+control of the main thread to operating systems that need it.
+
+Because Main is also blocking, the event loop of a Window must run in a goroutine.
+
+For example, to display a blank but otherwise functional window:
+
+	package main
+
+	import "gioui.org/app"
+
+	func main() {
+		go func() {
+			w := app.NewWindow()
+			for range w.Events() {
+			}
+		}()
+		app.Main()
+	}
+
+
+Event queue
+
+A Window's Queue method returns an ui.Queue implementation that distributes
+incoming events to the event handlers declared in the latest call to Update.
+See the gioui.org/ui package for more information about event handlers.
+
+*/
+package app