commits from bitcoin/master

[Bushstar]

Enable Travis checking for two Python linting rules we are currently not violating https://github.com/bitcoin/bitcoin/pull/13214

[wallet] Upgrade path for non-HD wallets to HD https://github.com/bitcoin/bitcoin/pull/12560

[tests] Remove spurious error log in p2p_segwit.py https://github.com/bitcoin/bitcoin/pull/13205

Add Clang thread safety annotations for variables guarded by cs_{rpcWarmup,nTimeOffset,warnings} https://github.com/bitcoin/bitcoin/pull/13116

wallet: Reset BerkeleyDB handle after connection fails https://github.com/bitcoin/bitcoin/pull/13161

wallet: Add compile time checking for cs_wallet runtime locking assertions https://github.com/bitcoin/bitcoin/pull/13081

Make --enable-debug to pick better options https://github.com/bitcoin/bitcoin/pull/13005

wallet: Add Clang thread safety annotations for variables guarded by cs_db https://github.com/bitcoin/bitcoin/pull/13127

mempool: Fix missing locking in CTxMemPool::check(…) and CTxMemPool::setSanityCheck(…) https://github.com/bitcoin/bitcoin/pull/11689

util: warn about ignored recursive -includeconf calls https://github.com/bitcoin/bitcoin/pull/13197

Fix Clang Static Analyzer warnings https://github.com/bitcoin/bitcoin/pull/12963

[Qt]: Improve sendcoinsdialog readability https://github.com/bitcoin/bitcoin/pull/13158

Break circular dependency: chain -> pow -> chain https://github.com/bitcoin/bitcoin/pull/13234

Minor optimizations to bech32::Decode(); add tests. https://github.com/bitcoin/bitcoin/pull/12881

scheduler: Add Clang thread safety annotations for variables guarded by m_cs_callbacks_pending https://github.com/bitcoin/bitcoin/pull/13125