feat(ios): support circular require references

STARTUP.md

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+# iOS vs Android startup notes
+
+## Android
+
+### Build time
+At SDK build time, `./android/titanium/prebuild.js` script is run which takes JS files (from `./android/runtime/common/src/js`) and generates C `char*`
+  - This is done to "bake in" the source to avoid disk I/O slowdown
+
+### Runtime
+`App.java`
+- create app info, set up encryption asset helper stuff
+- create asset cache
+- load Ti.App data into analytics class
+- create V8Runtime
+- register external modules (id -> class)
+- then call...
+
+`V8Runtime#nativeInit()`
+ - from java down to JNI
+ - sets up platform, isolate, debugger, then calls...
+`V8Runtime#bootstrap()`
+- sets up `EventEmitter` in C code
+- creates kroll object, calls into `KrollBindings.cpp` to hang `binding`/`externalBinding` functions for grabbing a builtin/native module
+- hangs `EventEmitter`, `DBG`, `runtime`, `log` method properties off `kroll` object
+  - (Note that `kroll.log` may not add newlines at end?)
+
+`kroll.js` is parsed then invoked
+- holds a function that does initial kernel bootstrapping
+- creates a `global.kroll` object
+- hangs `NativeModule` off of it which is a way to load the baked in JS code from build time
+- hangs `global.Ti` from loading baked-in `titanium.js`
+  - This ends up calling `KrollBindings#initTitanium()` which sets up `Proxy`/`KrollProxy`/`KrollModule`/`TitaniumModule` in C
+  - Also does bootsrapping of other baked in JS code for extensions like ui/network/properties/locale
+  - `bootstrap.js` file is loaded?!
+- hangs `global.Module` from loading baked-in `module.js`
+  - This effectively sets up our `require()` implementation
+- hangs `global.console` from loading baked-in `console.js`
+  - piggy-backs on `Ti.API`
+
+back to `V8Runtime#bootstrap()`
+- set up `global.global`
+- set default `global.__dirname` and `__filename`
+
+back to java `V8Runtime#initRuntime()`
+- start debugger
+- load external native modules
+
+... then?
+- The root splash screen activity `TiLaunchActivity` calls `TiApplication.launch()` to start the JS runtime.
+- which eventually calls from Java -> JNI -> C to `global.Module.runModule()` (or if we have a snapshot, it does `global._startSnapshot(global)`)
+- When `TiLaunchActivity` is destroyed, the JS runtime will be terminated.