This commit removes one assert from test-console.js in which we check that
process.stderr.write returns true. In the case of a dump to a file we cannot
guarantee this any longer now that it goes through fs.WriteStream.

flock(LOCK_EX) always fails with EBADF, use fcntl(F_SETLK) instead.

This modifies the TTYWrap constructor to add another argument specifying if
it's a readable or writable TTY . That is stdin or stdout. If a TTYWrap is
not readable then writes to it are blocking.

This makes process.stdout blocking.

Fixes #1844.

Fixes #1813

Does not support sending net.Server objects only raw TCPWrap objects.

Fixes #1840

Speeds up http_simple benchmark by about 1.0%

Fixes #1837.

Fixes #1838

Needs test.

Fixes test/simple/test-child-process-fork.js

Also remove unused src/stdio_wrap.cc

Fixes #1824.

Fixes #1831