Annoint code owners.

Divide the (mostly) top-level directories of Swift into areas of code
ownership, similarly to what we do in LLVM and Clang. As with LLVM and
Clang, this list will grow and evolve over time.

CODE_OWNERS.TXT

@@ -0,0 +1,53 @@
+This file is a list of the people responsible for ensuring that patches for a
+particular part of Swift are reviewed, either by themself or by someone else.
+They are also the gatekeepers for their part of Swift, with the final word on
+what goes in or not.
+
+The list is sorted by surname and formatted to allow easy grepping and
+beautification by scripts.  The fields are: name (N), email (E), web-address
+(W), PGP key ID and fingerprint (P), description (D), and snail-mail address
+(S).
+
+N: David Abrahams
+E: [email protected]
+D: Swift standard library
+
+N: David Farler
+E: [email protected]
+D: Markup, Swift Linux port
+
+N: Doug Gregor
+E: [email protected]
+D: AST, Basic, Parse, Sema
+
+N: Joe Groff
+E: [email protected]
+D: SIL, SILGen
+
+N: Argyrios Kyrzidis
+E: [email protected]
+D: IDE, SourceKit, swift-ide-test
+
+N: Chris Lattner
+E: [email protected]
+D: Everything in Swift not covered by someone else
+
+N: John McCall
+E: [email protected]
+D: Demangler, IRGen, Runtime
+
+N: Joe Pamer
+E: [email protected]
+D: Expression type checker (Sema/ConstraintSystem)
+
+N: Jordan Rose
+E: [email protected]
+D: ClangImporter, Serialization, (Objective-)C printer, Driver
+
+N: Nadav Rotem
+E: [email protected]
+D: SILAnalysis, SILPasses
+
+N: Anna Zaks
+E: [email protected]
+D: SIL diagnostics passes