swift234

Compile multiple files as one translation unit

1) This now works: swift -o foo.o *.swift
2) Errors/warnings are now correct: ".../OutputStream.swift:331:10:"

NOTES:
1) The name of the module is now inferred from -o when available.
2) I had to workaround a unexpected IRGen crash with '&&' in Slice.swift. Weird.
3) "Assemble" is now the default, not "GenerateLL".
4) 'import swift' still requires the 'cat *.swift > swift.swift' hack.

NEXT STEP:
Make 'clang -o foo *.swift' and 'clang -o foo.dylib *.swift' just work.

Swift SVN r4572