Issue 31 — Part 1

Quite some changes, but I think this releases #52 #39 (at least when I'm done with this one here on #31) and #75 for others to work on.
Bunch of tests to be added for #52 #39 and #75 as well... 
It could well be there was a value before there... I don't know. This brings it back in sync with the SoR. Yes, it may introduce an unnecessary miss (like if some newer data was written since), but this is a Cache, so the price is worth it.