POS is loading all partners, not only customers

Hi,

Adding domain to res.partner model, so POS only loads "customers"
[FIX] mrp_operation: missing context

It is present in mrp declaration but was not in mrp_production which was problematic if another module inherit as well from action_produce_end.
[FIX] payment: docstring typo

closes #3557
[FIX] doc: typo in themes document

closes #3874
[FIX] account: bank statement reconciliation widget: disable buttons which trigger RPC calls until done
[FIX] website_reseller: Navigation Broken for Partner List on Website issue#3522
[FIX] website_sale: Discussion not working on product; issue: #3495
[FIX] account: bank statement reconciliation widget: correct multicurrency display
[FIX] mrp: duplicated xmlid for ir.model.access
[IMP] account: bank statement reconciliation widget: allow to filter move lines on due date
[FIX] doc: remove a word that does not make sense

closes #3594
[FIX] sale_service: typo in string Thick -> Tick
[IMP] website_sale: performance on category page

public_categ_ids field was moved to product.template object
[Fix] ir_translation: fix the problem of base_field object has no attribute model (Maintenance Case:618054)

Fixes #3859
[FIX] product: keep attribute on a variant with only one attribute

When adding informational attribute, with only one possible value, it used to be skipped.
Instead keep it and add it on every variant.

To avoid dropping and recreating product (and lose eventual customisations), the attributes with only one possible value are set on every product.
This makes sure that in following test, these are not considered in variants_inactive variable.

Fixes #3204
[IMP] stock: display company in location tree view
[point_of_sale] Domain functions to literals

Replaced domain functions with literals where there are only constants
Merge pull request #3803 from TheCloneMaster/patch-7

POS is loading all partners, not only customers
[FIX] hr_attendance: use float division for worked_hours field

Used to be rounded to integer while the field is a float.
Fixes #3526
[FIX] sale_layout: set 0 as default value for categ_sequence

Otherwise, in some cases, the categ_sequence can be set to null, which is not ordered the same way than 0, and you won't be able to sort lines with null and 0 as categ_sequence between each others