doc: update options for exec and execFile

The stdio and customFds options are never used by exec or execFile,
remove them from the documentation for these functions.
build: only use DESTDIR instead of PREFIX for pkg

Preserve default install prefix seen in process.config, but use DESTDIR
for installing to deliniate 32/64 versions, avoid conflicts with PREFIX
settings in config.mk
test: report test duration in TAP progress
test: don't use total_seconds() because of py2.6
stream: make Readable.wrap support objectMode

Added a check to see if the stream is in objectMode before deciding
whether to include or exclude data from an old-style wrapped stream.
stream: make Readable.wrap support empty streams

This makes Readable.wrap behave properly when the wrapped stream ends
before emitting any data events.
doc: document stream.Writable 'error' event

Fixes #5255.
test: fix pummel/test-net-many-clients.js

client sockets no longer emit 'connect' event inside the
requestListener, update test-net-many-clients to reflect that
doc: s/search.npmjs.org/npmjs.org/
child_process: fix handle delivery

Commit 9352c19 ("child_process: don't emit same handle twice") trades
one bug for another.

Before said commit, a handle was sometimes delivered with messages it
didn't belong to.

The bug fix introduced another bug that needs some explaining. On UNIX
systems, handles are basically file descriptors that are passed around
with the sendmsg() and recvmsg() system calls, using auxiliary data
(SCM_RIGHTS) as the transport.

node.js and libuv depend on the fact that none of the supported systems
ever emit more than one SCM_RIGHTS message from a recvmsg() syscall.
That assumption is something we should probably address someday for the
sake of portability but that's a separate discussion.

So, SCM_RIGHTS messages are never coalesced. SCM_RIGHTS and normal
messages however _are_ coalesced. That is, recvmsg() might return this:

  recvmsg();  // { "message-with-fd", "message", "message" }

The operating system implicitly breaks pending messages along
SCM_RIGHTS boundaries. Most Unices break before such messages but Linux
also breaks _after_ them.  When the sender looks like this:

  sendmsg("message");
  sendmsg("message-with-fd");
  sendmsg("message");

Then on most Unices the receiver sees messages arriving like this:

  recvmsg();  // { "message" }
  recvmsg();  // { "message-with-fd", "message" }

The bug fix in commit 9352c19 assumes this behavior. On Linux however,
those messages can also come in like this:

  recvmsg();  // { "message", "message-with-fd" }
  recvmsg();  // { "message" }

In other words, it's incorrect to assume that the file descriptor is
always attached to the first message. This commit makes node wise up.

Fixes #5330.
Merge branch 'v0.10'

Conflicts:
	tools/test.py