This provides very memory-efficient CBOR stream parsing
and writing.

The parser  converts pieces of CBOR into callbacks that define
the structure and collate string and blobs into buffer chunks
for extensible and easy access.

It is fragementation-safe and does not need all the CBOR in
the same place at one time, chunks of CBOR are parsed and
discarded as provided.

It does not allocate and just needs a few hundred bytes of
stack for even huge CBOR objects.  Huge strings and blobs
are handled without needing memory to hold them atomically.

Includes ./minimal-examples/api-tests/api-test-lecp that
unit tests it against 82 official example CBORs and
26 additional test vectors from COSE (just checking the CBOR
parsing).

The writing apis allow printf style semantics with a variety
of CBOR-aware %-formats.  The apis write into a context that
manages output buffer usage, if the output buffer fills,
then the apis return with an AGAIN code that lets you issue
and reset the output buffer and repeat the api all to issue
more output.  The subsequent calls can occur much later or
from a different function context, so this is perfect for
WRITEABLE-mediated output from the network parts of lws.

See ./READMEs/README.cbor-lecp.md