remove Explicit from Should_set_the_newV4_flag
SetTransportThresholds moved to UnicastBus feature
make IInMemoryOperations error from 5.1

since we need to still return it in v5
finish removing MessageModule
Merge pull request #2190 from Particular/remove_MessageModule

finish removing MessageModule
Removing the gateway since its now a separate nuget. As part of this pull
a new option of DependsOn has been added to allow features to add non
strongly typed dependencieseparate nuget.

Closes #1603