RFC: int/uint portability to 16-bit CPUs

Both Issue #14758 and Issue #9940 call for RFCs.

This RFC summarizes those discussions, explains the core issue of
code portability to 16-bit CPUs (also of 64-bit code to 32-bit CPUs),
explains what's meant by "default" integer types, makes 2 specific
proposals, and proposes coding style for integer sizing.
A better phrasing: IoT is a class of embedded devices that's forecast to surpass the PC + tablet + phone units combined within 3 years and sell 9G units 4 years from now, and the biggest downside is threats to data & physical security.

http://www.businessinsider.com/the-internet-of-everything-2014-slide-deck-sai-2014-2?op=1

I don't want them programmed in C/C++.