swift234

Rename the standard library to "Swift" (instead of "swift")

This is more in line with all other modules currently on our system.
If/when we get our final name for the language, we're at least now set
up to rename the library without /too/ much trouble. (This is mostly just
a lot of searching for "import swift", "swift.", "'swift'", and '"swift"'.
The compiler itself is pretty much just using STDLIB_NAME consistently now,
per r13758.)

<rdar://problem/15972383>

Swift SVN r14001