Looks good to me! I like the changes.

In D1158#22790, @deadalnix wrote:

Please use clang-format 4.0 to format these files.

After May HF update default datacarriersize to 220 byte

After May HF update default datacarriersize to 220 byte

In D1158#22132, @schancel wrote:

You mean if they've already configured their client to accept non-standard transactions? Yes, we could check if the current configured value is the default of 83 and then swap to 223 at the time of the hardfork. This seems to be what you are suggesting?

IsStandard and IsStandardTx probably need to become stateful for future upgrades anyways. Might as well fix them now.

In D1158#21731, @deadalnix wrote:

This is important anyway. If mempools are not mostly uniform, then fast block propagation techniques such as compact block and XThin do not work anymore.

In D1158#21679, @deadalnix wrote:

Activation code and test ?