XX-3187 / Store backed checked rounds

network/checkedRounds.go

network/follow.go

network/manager.go

network/rounds/check.go

storage/reception/IdentityUse.go

storage/reception/fake_test.go

storage/reception/registration.go

storage/reception/store.go

storage/rounds/checkedRounds.go

storage/rounds/checkedRounds_test.go

storage/utility/blockStore.go

storage/utility/blockStore_test.go