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/runmain.go

@@ -0,0 +1,27 @@
+// +build android darwin,ios
+
+package app
+
+// Android only supports non-Java programs as c-shared libraries.
+// Unfortunately, Go does not run a program's main function in
+// library mode. To make Gio programs simpler and uniform, we'll
+// link to the main function here and call it from Java.
+
+import (
+	"sync"
+	_ "unsafe" // for go:linkname
+)
+
+//go:linkname mainMain main.main
+func mainMain()
+
+var runMainOnce sync.Once
+
+func runMain() {
+	runMainOnce.Do(func() {
+		// Indirect call, since the linker does not know the address of main when
+		// laying down this package.
+		fn := mainMain
+		go fn()
+	})
+}