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_ios.go

@@ -0,0 +1,10 @@
+// +build darwin,ios
+
+package app
+
+import "C"
+
+//export gio_runMain
+func gio_runMain() {
+	runMain()
+}