commits from bitcoin/master

[Bushstar]

Fix "gmake check" under OpenBSD 6.3 (probably *BSD): Avoid using GNU grep specific regexp handling https://github.com/bitcoin/bitcoin/pull/13355

[wallet] createwallet RPC - create new wallet at runtime https://github.com/bitcoin/bitcoin/pull/13058

qa: Fixup setting of PATH env var https://github.com/bitcoin/bitcoin/pull/13353

qa: Avoid checking reject code for now https://github.com/bitcoin/bitcoin/pull/13352

doc: split FreeBSD build instructions out of build-unix.md https://github.com/bitcoin/bitcoin/pull/13372

bench: Use non-throwing ParseDouble(...) instead of throwing boost::lexical_cast(...) https://github.com/bitcoin/bitcoin/pull/13383

Specialized double-SHA256 with 64 byte inputs with SSE4.1 and AVX2 https://github.com/bitcoin/bitcoin/pull/13191

Docs: Rename “OS X” to the newer “macOS” convention https://github.com/bitcoin/bitcoin/pull/13366

build: Guard against accidental introduction of new Boost dependencies https://github.com/bitcoin/bitcoin/pull/13385

wallet: Prevent segfault when sending to unspendable witness https://github.com/bitcoin/bitcoin/pull/13351

refactoring: Drop UpdateTransaction in favor of UpdateInput https://github.com/bitcoin/bitcoin/pull/13269

qa: Increase includeconf test coverage https://github.com/bitcoin/bitcoin/pull/13367

rpc: Remove the need to include rpc/blockchain.cpp in order to put GetDifficulty under test https://github.com/bitcoin/bitcoin/pull/13288