Refactor Exclude and Formula into Rule #2290

We keep only one kind of Rule, with a formula. This streamline computing
process and more importantly allow us to chain Exclude correctly amongst
other formulas
Split rule usages in two levels #2290

This allow us to compute Table_W/Table_S while ignoring rules used
in GraphData_W/GraphData_S for /browse/table/filter. And then use
all rules for /browse/table/questionnaire.

This give use better control of what is used when.
Detect when there is only data for total part #2290

We automatically disable complementary computing for total part, if
we find that there is no data available for other parts (and hence the
complementary computing would give NULL values).

This is useful for Saudi Arabia
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