* UMP: Update the impl guide

* UMP: Incorporate XCM related changes into the guide

* UMP: Data structures and configuration

* UMP: Initial plumbing

* UMP: Data layout

* UMP: Acceptance criteria & enactment

* UMP: Fix dispatcher bug and add the test for it

* UMP: Constrain the maximum size of an UMP message

This commit addresses the UMP part of https://github.com/paritytech/polkadot/issues/1869



* Fix failing test due to misconfiguration

* Make the type of RelayDispatchQueueSize be more apparent in the guide

* Revert renaming `max_upward_queue_capacity` to `max_upward_queue_count`

* convert spaces to tabs

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

* Update runtime/parachains/src/router/ump.rs

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

* add storage for approvals module

* basics of approval logic

* fix links

* Session info module

* create an approvals_inherent module

* integrate approvals module with inclusion

* Remove approvals runtime

* tweak mentions of on-chain logic

* add note on finality-grandpa voting rule

* elaborate on node-side components

* stub for availability recovery

* add another note on voting rule

* Beginnings of approval subsystems

* flesh out approval voting now

* logic for checking assignment certs

* initial scheduler logic

* scheduler logic

* adjst tranche taking logic

* approval voting import

* approval work (voting side)

* amend some TODOs

* mark some TODOs

* describe `ApprovedAncestor`

* reference protocol-approval.md

* clarity on bitfield

* remove approvals_inherent

* tweak session_info module according to review

* formatting & nits

Co-authored-by: Robert Habermeier <robert@Roberts-MacBook-Pro.local>

* remove pending TODO after the DMP impl merge

* DMP: Update the impl guide

* DMP: Incorporate XCM related changes into the guide

This is the DMP related part of https://github.com/paritytech/polkadot/issues/1702

* Guide: Reindent the router module with 4 spaces

The guide used to use 2 spaces for indentation. The problem with that is `mdbook` doesn't recognize them as a proper indentation and thus doesn't render indent properly.

A couple of things are not indented here because they will be changed in the following commits

* Guide: a bunch of fixes

Limit the number of channels a para can have.

Split HrmpTransientValidationData and add stuff.

* Take 2 at the upward messages

* Trying to restore stuff from unsuccesful rebase

* Fix whitespace

* Clean up

* Change rustdoc to comment

* Pivot to a less stricter, w.r.t. to acceptance, model

* Rename `max_upward_message_num_per_candidate`

* Update docs for DownwardMessage

* Apply suggestions from code review

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* Rephrase "Dispatchable objects ready to ..."

* Finish the sentence

* Add a note about imprecision of the current weight formula

* Elaborate on potential use-cases for the upward message kinds.

* s/later/below

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* First stab at downward messages.

That also includes a notion of horizontal messages.

* Add some structure to the router.

* Update `ValidationOutputs`

* Add `processed_downward_messages` to `ValidationOutputs`.

Forgot to check that in.

* s/AccountId/ParaId

* DownwardMessage::ParachainSpecfic

* s/ensure_horizontal_messages_fits/ensure_horizontal_messages_fit

* Clarify that Router called for each candidate

* Update the preamble for Router.

* Rewrite the relay-chain extrinsic routines

* Update gloassary

* Add DMP to the glossary

* If the queue is empty, `processed_downward_messages` can be 0

* WIP

* Add condemned list

* Pivot to message-storing channel based HRMP

* Finished draft

* Tidy up

* Remove a duplicate glossary entry

* Fix typo

* Fix wording to emphasize that the channel is unidirectional

* Proper decrement `HrmpOpenChannelRequestCount`

* Add a comment for `HrmpOpenChannelRequestCount`.

* Remove old configuration values.

* Be more specific about the para{chain,thread} hrmp chan limits.

* Fix indentation so the lists are rendendered properly

* "to answer **the**" question instead of "a"

* Add a missing call to `check_processed_downward_messages`

* Clean more stuff during offboarding

* Fix typo

* Fix typo for the config

* Add a call to `prune_dmq`

* Add explicit invariants for ingress/egress indexes

* Add comments for the sender/reciever deposit config fields

* Document various fields and structs in Router module

* More docs

* Missing docs in Candidate.md

* Tabs to spaces in router.md

* Apply Rob's suggestion

* Add the hrmp_ prefix to the router messages

* Those are entry points

* Use SessionIndex type for the `age` field

* Use a struct to represent `HrmpChannelId`

* Put only MQCs into the LocalValidationData

* Close request can be initiated by the runtime directly

* Close request can be initiated by the runtime directly

* tabs/spaces

* Maintain the list of the outgoing paras in Router

* Update roadmap/implementers-guide/src/runtime/inclusion.md

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* fix typo

* Remove an unnecessary pair of code quotes

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* runtime: rename parachain_rotation_frequency to group_rotation_frequency

* scheduler: handle timeouts for no group rotation

* scheduler: apply fixes from code review

* scheduler: remove my comments

* rename implementor's guide to implementer's guide

* fix typos in more places

* Router module initial commit

* Add the router.md itself

* Enqueue only on enact_candidate

* Initialization concerns

* Ignore the snippet

* Update roadmap/implementors-guide/src/runtime/router.md

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* Dispatch messages on finalization

* More fixes from review

* Update roadmap/implementors-guide/src/SUMMARY.md

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* Adds router to initializer order

* Adds messages.md

Co-authored-by: Robert Habermeier <rphmeier@gmail.com>

* types chapter & candidate types

* Factor out some message types

* backing and availability types.

* spacing

* finish thought

* info on signed payloads

* update links

* explicit wrapper types

* add remaining message types

* add runtime API subsystem

* adjust language

* tweak candidate validation message

* find homes for some misfit types

* embed abridged within full candidate receipt

* Update roadmap/implementors-guide/src/SUMMARY.md

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* Update roadmap/implementors-guide/src/SUMMARY.md

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* adjust text on candidate selection message to match

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>