Counting all documents matching some criterion has a cost proportional to
the number of those documents. Modules grow large easily (the effect
becomes quite noticeable from ~50k), and this information costs too much.

Provide compatibility with non-upgraded products.
Also, update erp5_l10n_fr translation.

Allows telling user whether what he sees is the whole result set, or just
a limited sample of it.

because they are mostly used in non-web mode.

This is also fixes the case where an old version of ERP5Site_reindexAll is used,
when erp5_core is not the first BT being updated.

If PATH environment variable is not defined, this Products cannot be
imported. Followup of 399f95f9.

There are a lot of misses in this function because related keys must have
precedence over homonym columns, which makes it cost a *lot* of cpu time
to just return None.

Not perfect yet (what if definitions change during the same transaction ?),
but better than previous state.

it was creating local properties

With this, is possible set custom references without overwrite accounting_workflow

- The interface says that getConversionSize raises a KeyError when this cache
  does not exist. Update implementation accordingly.
- update getConversion to always return a string for the data. The caller
  should not have to worry about the data format.
- warn when an OFS.Image is passed to setConversion