wireproto: syntax for encoding CBOR into frames We just vendored a library for encoding and decoding the CBOR data format. While the intent of that vendor was to support state files, CBOR is really a nice data format. It is extensible and compact. I've been feeling dirty inventing my own data formats for frame payloads. While custom formats can always beat out a generic format, there is a cost to be paid in terms of implementation, comprehension, etc. CBOR is compact enough that I'm not too worried about efficiency loss. I think the benefits of using a standardized format outweigh rolling our own formats. So I plan to make heavy use of CBOR in the wire protocol going forward. This commit introduces support for encoding CBOR data in frame payloads to our function to make a frame from a human string. We do need to employ some low-level Python code in order to evaluate a string as a Python expression. But other than that, this should hopefully be pretty straightforward. Unit tests for this function have been added. Differential Revision: https://phab.mercurial-scm.org/D2948