fa9461473 [doc] dev-notes: Members should be initialized (MarcoFalke)
Pull request description:
Also, remove mention of threads that were removed long ago. Motivation: Make it easier to spot bugs such as #11654 and #12426
Partial (mostly) backport of Core PR12434
This diff brings this section of the developer-notes up-to-date with recent backporting efforts (~mid 2018) but retains the -Wshadow documentation applicable to ABC.
It includes some documentation additions from https://github.com/bitcoin/bitcoin/pull/8794/files#diff-e4de6d71249c78e229a61d6a03ac255a
and skips backporting https://github.com/MarcoFalke/bitcoin/commit/f203ecc621c0af594c43c7fce8a765a8259e3b43