Make StepMania compile in Xcode 5.1.1

project:

- Mac OS X 10.6 SDK is used.
- Architecture has been set to 32-bit. Otherwise, `MemoryCardDriverThreaded_MacOSX` and `HIDDevice` will not compile.
- Replaced the outdated `README` file with a new `README.md`.

libmad:

- Use FPM_64BIT instead of FPM_INTEL. Otherwise, it will not compile. Also, latest Xcode seems not to support `$(...)` expansion in defining macros. Instead, they are hardcoded in the build settings.

stepmania:

- Removed compiler flags `-finline-limit` and `-falign-loops=16`

Xcode/README.md

@@ -0,0 +1,11 @@
+
+StepMania Xcode Project
+=======================
+
+
+Mac OS X 10.6 SDK
+-----------------
+
+StepMania requires Mac OS X 10.6 SDK to build.
+See this [comment](https://github.com/stepmania/stepmania/issues/224#issuecomment-48857894) on how to install 10.6 SDK in Xcode.
+