Add on numeric widget an attribute for grouping

Some numeric field should not be grouped like a year (extracted from a date) or an ID.

assigned to @ced

added sao tryton trytond ~844 + 1 deleted label

Here is review355501002. I updated timesheet and sale_opportunity to use Integer and disable grouping. If anyone find another case where this feature could be used, please tell me.

added 1 deleted label and removed 1 deleted label

New review355501002 at https://codereview.tryton.org/355501002/#ps363911002

New changeset 5f6f70ade3bd by Cédric Krier in branch 'default':
Use integer without grouping for year reporting
https://hg.tryton.org/modules/sale_opportunity/rev/5f6f70ade3bd

added 1 deleted label and removed 1 deleted label

closed

New changeset bd2ad24a9d5c by Cédric Krier in branch 'default':
Use integer without grouping for year and week reporting
https://hg.tryton.org/modules/timesheet/rev/bd2ad24a9d5c

New changeset 11a73b21aeca by Cédric Krier in branch 'default':
Add grouping attribute to numeric widgets
https://hg.tryton.org/sao/rev/11a73b21aeca

New changeset 01c176e7ef01 by Cédric Krier in branch 'default':
Add grouping attribute to numeric widgets
https://hg.tryton.org/tryton/rev/01c176e7ef01

New changeset fa011504c7f1 by Cédric Krier in branch 'default':
Add grouping attribute to numeric widgets
https://hg.tryton.org/trytond/rev/fa011504c7f1

New changeset 062ef9153bc5 by Cédric Krier in branch 'default':
Add grouping attribute to numeric widgets
https://hg.tryton.org/tryton-env/rev/062ef9153bc5