This will be used in UDP.  It also lets us reduce some unnecessary
code paths for redundant library initialization.

This adds endian awareness at compile time, and defines some little
endian versions of some macros. We antiicpate making more use of
little endian in new protocols to reduce the "endian tax", as nearly
every modern system is little endian these days.

This is the initial implementation of UDP transport.
It does in order guarantees (and consequently filters duplicates),
but it does not guarantee delivery.  The protocol limits payloads
to 65000 bytes (minus headers for SP), but you really want to
keep it to much less -- probably best for short messages that within
a single MTU to avoid IP fragmentation and reassembly.

This is unicast only for now (although there are plans for some
support for multicast and broadcast as well as being able to
perform automatic mesh building, but that will be in following work.

Additional tunables are coming.  This is only lightly tested at
this point, and should be considered experimental.  Its also undocumented.