* Fixes issue 181.

* Refactors add_hello and adds unit tests.

* Adds endian to the list of dependencies

* Make the library modular usable.

* Some fixes in the article about the costs of async abstractions [skip ci]

* Switch to library requirements instead of source. As source puts extra source in install targets.

* Add missing import-search for cconfig/predef checks.

* Add requires-b2 check to top-level build file.

* Bump B2 require to 5.2

* Move inter-lib dependencies to a project variable and into the build targets.

* Update build deps.

* Fix spurious semi-colon.

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Co-authored-by: Marcelo Zimbres <mzimbres@gmail.com>

As the user points out in

   #205

wait_for_all might be the cause of delay in the
reconnection. I could not observe any improvement in my
local setup but wait_for_one_error look the correct token
and all tests pass so I am willing to change it.

See #210.