Also creates a dedicated file for the message log.

Ideally, this would be generic. Unfortunately, the generic API serde 
doesn't natively support borsh, nor SCALE, and while there is a serde 
SCALE crate, it's old. While it may be complete, it's not worth working 
with.

While we could still grab bincode, and a variety of other formats, it 
wasn't worth it to go custom and for Serai, we'll be using SCALE almost 
everywhere anyways.

Greatly simplifies verifying when syncing.

Restores sig aggregation API.

For a hash, which is fixed-size, these should be the same yet this helps 
move past the dependency on SCALE. It also, for any type where the two 
values are different, smooths integration.

Also attempts to make the code more readable while updating/correcting 
documentation.

Greatly increases safety as well by ensuring only one message is 
processed at once.

1) Commit didn't include the round, leaving the clock in question.

2) Machines started with a local time, instead of a proper start time.

3) Machines immediately started the next block instead of waiting for 
the block time.

Unfortunately, this immediately makes Tendermint machine capable of 
deployment as  crate since it uses a git reference. In the future, a 
Cargo.toml patch section for serai/substrate should be investigated. 
This is being done regardless as it's the quickest way forward and this 
is for Serai.

Multiple traits exist to verify/handle blocks. I'm unsure exactly when 
each will be called in the pipeline, so the easiest solution is to have 
every step run every check.

That would be extremely computationally expensive if we ran EVERY check, 
yet we rely on Substrate for execution (and according checks), which are 
limited to just the actual import function.

Since we're calling this code from many places, it makes sense for it to 
be consolidated under TendermintImport.

Not possible to be used as the previous consensus could. It will not
produce blocks nor does it currenly even instantiate a machine. This is
just he next step.

This is incompatible with Substrate's expectations, yet should be valid 
for ours

This shouldn't be used as a library AFAIK. While runtime should be, and 
arguably should even be published, I have yet to see node in the same 
way. Helps tighten API boundaries.

Enables progress.

Doesn't wait for the response yet, which it needs to.

The BasicQueue returned obscures the TendermintImport struct. 
Accordingly, a Future scoped with access is returned upwards, which when 
awaited will create the machine. This makes creating the machine 
optional while maintaining scope boundaries.

Is sufficient to create a 1-node net which produces and finalizes 
blocks.

Also don't broadcast blocks which were solely proposed.

Removes JustificationImport as it should never be used.

By claiming File, they're not sent ovber the P2P network before they 
have a justification, as desired. Unfortunately, they never were. This 
works around that.

Substrate doesn't expect nor officially support children with less work 
than their parents. It's a trick used here. Accordingly, ensure the 
trick's validity.

The machine reset to the end time of the current round. For a delayed 
network connection, a machine may move ahead in rounds and only later 
realize a prior round succeeded. Despite acknowledging that round's 
success, it would maintain its delay when moving to the next block, 
bricking it.

Done by tracking the end time for each round as they occur.

The round was usable to build the current clock in an accumulated 
fashion, relative to the previous round. The end time is the absolute 
metric of it, which can be used to calculate the round number (with all 
previous end times).

Substrate now builds off the best block, not genesis, using the end time 
included in the justification to start its machine in a synchronized 
state.

Knowing the end time of a round, or the round in which block was 
committed to, is necessary for nodes to sync up with Tendermint. 
Encoding it in the commit ensures it's long lasting and makes it readily 
available, without the load of an entire transaction.

…changes

At some point, the modulus was removed causing it to exceed the 
validators list and stop proposing.

The Tendermint machine uses the passed in number as the block's being 
worked on number. Substrate passed in the already finalized block's 
number.

Also updates misc comments.

Enables passing data in, such as the network.

Provides an explicitly clear API clearer to program around.

Also adds additional time code to handle an edge case.

It's not used there at all.

These two files were largely the same, just hooking into sync structs 
with almost identical imports. As this project shapes up, removing dead 
weight is appreciated.

Renames serai-consensus to sc_tendermint

We test their equivalency yet still better to use finalized_* in 
general.

Some relation to #95.