[FIX] some badly implemented function fields return empty strings (for e.g. dates, instead of False)
[FIX] some badly implemented function fields return empty strings (for e.g. dates, instead of False)

treat empty strings as 'false' except for char fields

havt/openerp-web,havt/openerp-web,havt/openerp-web,havt/openerp-web,akretion/openerp-web,havt/openerp-web,akretion/openerp-web,akretion/openerp-web