fix typo on undeclared variable xml_id
Merge pull request #2113 from yvaucher/8.0-fix-ir_model-undefined-xml_id

fix typo on undeclared variable xml_id
[FIX] crm: lead_to_opportunities, check that current active_id has not been already merged by another previous active_id. Else, we was trying to browse an lead which was already deleted by a previous merge in the same loop.
[FIX] account, bank statement reconciliation: payment and invoice in foreign currency use case fixed
[FIX] l10n_be_coda: if there's no communication, feed the field with '/' instead of an empty string
[IMP] sales_team: remove widget many2many_kanban from "Team Members" tab. Need to fix the security check from many2many_kanban before to reuse-it. Was checking delete user, and not write sale_team when we were tyring to delete a sale_men (user) from member_ids.
[IMP] sales_team: Force a tree view in Sales team tab to avoid to show unnecessary informations like last login date
[FIX] website_sale: pay now button should be translatable
[FIX] survey: trace the partner_id taking the survey; if no token, set as the current user's partner.
[FIX] account, bank statement reconciliation: fixed use cases involving transactions made in a different currency than the company AND the statement ones
[ADD] initial theme guide + scaffolding

incomplete, incorrect, committed for testing
[FIX] fields: avoid prefetching of one2many fields

When reading a one2many field, the inverse mapping of the lines (matching m2o -> lines of corresponding record) was instantiating each line and then triggering the prefect of fields.
To improve the performances, the inverse mapping is done in sql to avoid triggering the prefetching.
[IMP] fields: update inverse fields lazily for performance

When a relational field is assigned in an onchange, its inverse field is
updated in cache.  Reading the current value of the inverse field may be
costly, for instance in the case of a one2many field with thousands of records
as a value.  Instead, put in cache a SpecialValue that reads and updates the
field; it will be triggered only when it is accessed.
[IMP] models: do not prefetch too many records at once
[IMP] models: prefetch fields with groups (those to which user has access)