Partial solution to NaCl build.
First version which builds a .nexe file!
First version that actually runs something!

...although it just crashes with an assert failure (argc > 0), which is
actually progress.
First version which actually runs!

Although it doesn't do anything useful, at least it doesn't crash.
Fix bug in JS to make the whole test actually do the right thing.
Now main (nay mosh_main) is called, and the program attempts to do something.

There's no useful I/O yet, but the program doesn't exit, which means it
probably thinks it is doing something.
Runs up to the not-implemented socket() call.

This is a lot of wild stubbing, just to see how far it would get, and what
hurdles must be crossed. Careful thinking about how best to do this will be
needed.
Stub out socket calls.

Looks like I can wrap all the network functionality via overriding socket
calls.
Clean up initialization code.

* Get init code out of Instance constructor.
* Move client to its own thread.
* Allow passing of parameters via embed tag attributes.
Wrap up everything into a packaged app.

This is necessary to get the permission to talk UDP.
Rework a bit to make the code work more correctly.

While no data is yet communicated, this stubs out things well enough for
mosh-client to believe it is sending packets to nowhere, which causes it to
have the expected behavior of timing out. This, with some other changes, sets
up the basic structure for hooking up the communication with JS.

Notably, this required munging some original Mosh code, specifically the
randomness code of PRNG; this will need to be addressed.
Initial implementation of PepperPOSIX::Selector.
Make debugging easier across modules.
Fix bug with timeout usage in pselect_cond_timedwait().
Implement stub version of UDP I/O class, and wire it into POSIX overrides.
Fix MakeAddress and move it out of extern "C".
Comment out bind() and friends, as it may not be necessary.

Also clean out some old commented debug code.
Move calculation of timeout to as early as possible.
Automate generation of NaCl Manifest.
Change JSUDP to StubUDP, as it probably won't get implemented.