clean how we deal with Stamps in the HUB

[letypequividelespoubelles]

Currently we give to CommonValues (ie to a section):

• the current Stamps
• but we just need the hubStamp, and the logStamp (for the first section of a tx, or for logSection)

MmuStamp & MxpStamp increased at commit time, but don't use the Stamps of the CommonValues : as the Stamps is a field of the State it's a StackedList, and thus we spin off the Stamps when we enter a tx. But it means, it's a different pointer for the Stamps in the commonValues, and the one we increase (and actually trace), which is stupid.

What we have now is working but is ugly and not understandable, need to clean this mess.