Client fixes, poll for unique last id and cache clients

[sakridge]

So we don't keep running up the port range

[garious]

Cool, but this makes it clear that we no longer have a client demo. It's a set of clients, working their hardest to beat up on fullnode. Can you document that somewhere? In the readme and/or the client-demo module documentation. We should consider renaming the module to make space for a far simpler client demo. multiclient-demo.rs?

[garious]

Can you rebase on #435 after it goes in? It fixes 1 of 2 CI problems, and the 2nd is easy to spot/ignore.

[sakridge]

That has been the case for a while that we use multiple threads. User can pass -t to just get one thread.

[sakridge]

and yes, will rebase

[garious]

Ready for rebase

[codecov]

Codecov Report

Merging #434 into master will decrease coverage by 0.16%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #434      +/-   ##
==========================================
- Coverage   91.15%   90.99%   -0.17%     
==========================================
  Files          36       36              
  Lines        3583     3541      -42     
==========================================
- Hits         3266     3222      -44     
- Misses        317      319       +2

Impacted Files	Coverage Δ
src/entry_writer.rs	82.85% <0%> (-5.72%)	⬇️
src/crdt.rs	86.01% <0%> (-0.81%)	⬇️
src/server.rs	94.5% <0%> (+0.12%)	⬆️

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[garious]

@sakridge, rebase to run the latest CI, which is now quick and stable.

[garious]

Merged in #440