Dedicated central output writing path

All output goes through a central point.  This is the start of a dramatic
refactoring which makes it much easier to track what goes on in npm when
it is used programmagically.

lib/utils/output.js

@@ -0,0 +1,63 @@
+
+// centralized stdout writer.
+
+exports.doColor = doColor
+exports.write = write
+
+var npm = require("../../npm")
+  , stdio = process.binding("stdio")
+  , streams = {}
+  , colored = {}
+  , net = require("net")
+  , sys = require("./sys")
+
+function doColor (stream) {
+  if (!npm.config.get("color")) return false
+  if (!stdio.isatty) return true
+  if (stream && stream.fd) stream = stream.fd
+  if (stream in colored) return colored[stream]
+  return colored[stream] = stdio.isatty(stream)
+}
+
+function write (stream, args, cb) {
+  stream = getStream(stream)
+  if (!stream) return
+  if (!Array.isArray(args)) args = [args]
+  var msg = ""
+    , colored = doColor(stream)
+  args.forEach(function (arg) {
+    msg += " "
+    if (typeof arg !== "string") {
+      msg += sys.inspect(arg, false, 5, colored) + "\n"
+    } else {
+      if (!colored) arg = arg.replace(/\033\[[0-9;]+m/g, '')
+      msg += arg
+    }
+  })
+  // use the \r\n in case we're in raw mode.
+  msg = (msg.trim() + "\n").split(/\r?\n/).join("\r\n")
+  var flushed = stream.write(msg)
+  if (!cb) return flushed
+  if (flushed) return cb(), true
+  stream.on("drain", function D () {
+    stream.removeListener("drain", D)
+    cb()
+  })
+  return false
+}
+
+function getStream (fd) {
+  var stream
+  if (!fd && fd !== 0) return
+  if (typeof fd === "string") fd = +fd
+  if (fd && typeof fd === "object") {
+    stream = fd
+    fd = fd.fd
+  } else if (streams[fd]) {
+    stream = streams[fd]
+  } else try {
+    stream = new net.Stream(fd)
+  } catch (ex) {}
+  if (!stream || !stream.writable) return
+  return streams[fd] = stream
+}