backport: merge bitcoin-core/gui#337, #354, #317, #349, #403, #418, #416, #449, #477, #563, #554, #615 (qt backports: part 2)

backport: merge bitcoin-core/gui#337, #354, #317, #349, #403, #418, #416, #449, #477, #563, #554, #615 (qt backports: part 2) #882