Merge #8515: A few mempool removal optimizations
0334430 Add some missing includes (Pieter Wuille)
4100499 Return shared_ptr<CTransaction> from mempool removes (Pieter Wuille)
51f2783 Make removed and conflicted arguments optional to remove (Pieter Wuille)
f48211b Bypass removeRecursive in removeForReorg (Pieter Wuille)