Expose whether total_size is the same as limit.

Allows telling user whether what he sees is the whole result set, or just
a limited sample of it.
Tell user when he is only viewing a sample of a larger object set.

Provide compatibility with non-upgraded products.
Also, update erp5_l10n_fr translation.
Do not provide a count_method by default.

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.