Document SHOULDs for authority required protocol lists

See merge request !365

Fix an arithmetic error in prop359

See merge request !366

prop359: fix typos in DEC_UIV

See merge request !363

Proposal 360: Limiting HSDesc size and amplification

See merge request !362

Fix copy-paste errors in socks-extensions.md

See merge request !361

Spotted by Jeremy Rand

s/MicroDesc/Microdesc/ where it appears

See merge request !360

New proposal 359: counter galois onion

Closes #186

See merge request !359

Related to arti#1923.

Revisions to prop346 and accompanying spec tweaks

See merge request !358

Prop344: Update and Categorize Vectors; Ground in Threat Model

See merge request !355

Prop#349: Decouple validation from prop#340 packing

See merge request !262

If we specify the state machines independently from prop#340, everything ends
up cleaner.

Specify that the given parameters don't exist automatically.

Explain how to apply them to onion services.

They don't belong here; this proposal is for negotiating  _new_ features.
Migrating from existing extensions isn't specified here.

It seems cleaner to have it match router descriptors.

This is analogous to our earlier tor-spec cleanup in
0fada728.

We don't want to call these things "versions";
we've already updated the rest of torspec accordingly in !352.

Also, clarify the implications of the cases where subprotocol flags
_do_ correspond to versions.

We need to keep this in sync with the extand protocols,
so it belongs in the spec.

We aren't doing this in-protocol for tor-vpn; so apparently
it doesn't get a subprotocol.

Per prop346, subprotocol numbers are _flags_, so it's okay to use a
Relay=X flag to indicate support for this cell format.

rend-spec: add a note about replay detection

Closes #246

See merge request !349

Explain why we're doing it, and the extent to which we do
(or do not) need to be perfect.

Closes #246.

proposal 355: Add a couple of footnotes

See merge request !357

Based on discussions at !356.

A couple minor spelling/grammar corrections.

See merge request !356

Proposal 358: unify the circuit handshake extensions

See merge request !354