Every message sent through send_message or the entity paths needed a
proto_encode_msg<T> thunk (17 bytes on xtensa) and, for entity state
and info messages, a calc_size<T> thunk, because the generated encode
and calculate_size were member functions and the connection code wants
plain function pointers over const void *.
The generator now emits the bodies as static encode_msg(const void *)
and calc_size_msg(const void *) functions, so &T::encode_msg is
already a MessageEncodeFn and the thunks disappear. The member
encode() and calculate_size() remain as inline forwarders for direct
callers. ProtoMessage carries the same static defaults for messages
without fields, which also removes the separate no-op encode thunk.
The fixed32 store helper moves to a private section since it neither bounds checks nor
advances the cursor, its comment describes the path each target takes, the generated
file scan flags any ProtoEncode call that does not assign the cursor, and StateWaiter
timeouts can carry a label so gathered waits are told apart.
A call that drops the returned cursor would silently truncate the message, so the
compiler now warns on it and a unit test scans the generated file for the same mistake.
Also corrects the outlining comment for ESP8266, where the inline write is a few byte
stores rather than one, and the RAW_ENCODE_MAP annotation.
J. Nick Koston