[feature] delimit preamble from ciphertext

We now encode preamble and ciphertext+hmac in two distinct payloads
separated by a space. This allows metadata to be extracted and used
before decoding the whole document.
It also introduces a single packer for packing and unpacking of data
instead of reads and writes. Downside: doc_id and rev are limited to 255
chars now.

0 files changed, 0 insertions, 0 deletions