Do not flush the cache after every block outside of IBD
Use unordered_map for CCoinsViewCache with salted hash
Merge pull request #4494

bc42503 Use unordered_map for CCoinsViewCache with salted hash (Pieter Wuille)
Merge pull request #4505

d4d3fbd Do not flush the cache after every block outside of IBD (Pieter Wuille)
[Qt] Prevent balloon-spam after rescan