stdlib/printing: replace four printing systems with one new one

The old ones were:

- print/println
- printAny
- printf
- Console

The new printing story is just print/println.  Every object can be printed.
You can customize the way it is printed by adopting Printable protocol.  Full
details in comments inside stdlib/core/OutputStream.swift.

Printing is not completely finished yet.  We still have ReplPrintable, which
should be removed, string interpolation still uses String constructors, and
printing objects that don't conform to Printable will result in printing
mangled names.


Swift SVN r18001

test/stdlib/NSStringAPI.swift

@@ -11,7 +11,7 @@ func testFindFileAndURL(path: String) {
   var content = String.stringWithContentsOfFile(
     path, usedEncoding: &usedEncoding, error: &err)
   
-  println("error: " + (err ? err!.description : "<no error>"))
+  println("error: " + (err ? err.description : "<no error>"))
   println("content: " + (content ? content!.lines[0] : "<no content>"))
 
   var url = NSURL.URLWithString("file://" + path)
@@ -20,7 +20,7 @@ func testFindFileAndURL(path: String) {
   content = String.stringWithContentsOfURL(
     url, usedEncoding: &usedEncoding, error: &err)
   
-  println("error: " + (err ? err!.description : "<no error>"))
+  println("error: " + (err ? err.description : "<no error>"))
   println("content: " + (content ? content!.lines[0] : "<no content>"))
   
 }