Surface water should fall back on later year result #2360

Our custom syntax did not allow to refer to another year result, hence
Surface water incorrectly did no fall back on next year result, leading
to NULL values, whereas it should have extended all the way back to first year.
Other Improved should be computed even if POP is absent #2360
Replace hardcoded complementary total with formula #2360

We used to hardcode the fact that high filters results for total part
was the sum of other parts. However, this is not always the case. By moving
this kind of behavior to Rule's formulas, we simplify our codebase while
giving enough flexibility to fullfill all use cases.

In particular this allow us to get correct results for Afghanistan.s
Extend regression in the past #2360

Forgot a cases present in Excel files where regressions should be
extented into the past if the value is either 0 or 1. This fixes
mistakes for both Bangladesh and Afghanistan