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.
First stubbed version of NativeUDP.
Provide quicker build times with a "fast" option.
First version that actually sends UDP packets. Does not receive yet.
Packets now come in and out, but not fully plumbed through.
First version that truly communicates.

Mosh exits after getting the initial frame; not sure why.
Also, this includes some style cleanup.
Emulate STDIN a little bit to see some back-and-forth comms.
Clean out some noisy debugs.
Rudamentary input support through browser window.

This does not handle pselect() properly. It depends entirely on getting data
from the network for any keyboard input to make it out.

This also does not grab all keys, as the keypress event doesn't capture
everything. I will save this for when I integrate with hterm.
Use a proper Target to manage pselect() emulation for keyboard input.