Can import several questionnaires for a single survey #2126

We used to assume that imported surveys had only one questionnaire. This
is wrong for Russia (RLMS96). This commit allow to import several questionnaires
for a same survey that appears several time in Excel files.

It also means that from now on, we cannot re-import data to overwrite them,
because it will always create new questionnaires.
Computation now support several questionnaires for one survey #2126

We used to use survey code as key element to identify questionnaire,
which made impossible to have several questionnaires for a single
survey on a chart. We now use questionnaire ID as key to avoid confusion
and be more robust.

Also NumericJson now use more robust regexp to supporting quotes
Use suffix for questionnaire point as well