docs/internal: get API spec up to date for 1.1 release
docs/internal: get API spec up to date for 1.1 release

This commit attempts to update the Swagger API spec to reflect deprecations
and additions to the API due to the upcoming 1.1 release. It covers the
following changes:

- Addition of receivers, and deprecation of control programs as a top-level
API object
- Addition of output IDs, and deprecation of txid/position pairs

Closes #501

chain/chain,chain/chain,chain/chain,chain/chain,chain/chain,chain/chain