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- Replaced the outdated `README` file with a new `README.md`.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`
Added Sprite::NewBlankSprite for use by NoteSkinManager.  Removed default texture loading from Sprite::Sprite.  Should fix problems with white banners and garbage on videos.
add missing nextrow character for options rows
make a note about DirectX 9 in the NSIS installer script
(I'm not sure how to fix it just yet)
DX8->DX9 in the rarely updated Manual
fix really awkward positioning of this line (was using spaces instead of tabs)
add note
Merge branch 'master' of https://github.com/stepmania/stepmania into xcode5.1.1
Merge pull request #234 from dtinth/xcode5.1.1

Make StepMania compile in Xcode 5.1.1
Fixed UpdateHasteRate and PlayerInfo:GetLifeMeter to check whether the life meter is null before using it.
make [ScreenHowToPlay] CharacterName metric work again
[Themes/default] hack for SWME StageDisplay to show correct stage on Normal Mode Evaluation
Improved three-key support.  Default theme should be completely usable with three-key cabinets if ThreeKeyNavigation pref is true.  Added ThreeKeyNavigation pref.  ScreenOptions:NavigationMode metric now uses that pref to decide between normal and toggle modes.  Added GoToFirstOnStart to OptionRowHandlerLua so an option row can control that behavior.  Rewrote input for default's ScreenSelectProfile to use an input callback to take advantage of menu button mapping.  Fixed inconsistent indentation in ORHL documentation.
update ScreenGameOver with a fancier "game over" graphic and bigger text
explicit float postfix added to some numbers in order to get visual studio to shut up
fix ActorScroller wrapping

looping actor scrollers would never reach destination items with number
higher than the number of items.
we dropped Visual C++ 6 support a long time ago, so remove most of the boolean operator hacks.
However, the == one is still required (at least on Visual Studio 2008, not sure about others).
Feel free to revert this if it's causing problems elsewhere.
telling Visual Studio to shut up about more warnings wrt/double and float
Merge pull request #245 from sigatrev/ActorScroller

fix ActorScroller wrapping
Changed GameCommand screen validation to allow OptionsList to work again.