[FIX] web: chain close action on wizard confirm

If a wizard has several steps, or laucnh a second wizard, the view from where has been loaded the initial wizard is finally reloaded
[IMP] Optimize the schedulers of the calendar, fetchmail and base_action_rules modules

Disable the the crons when they'd have nothing to do, re-enable them when a
task is (probably) introduced
[FIX] account_payment: lin2bank correct fallback condition
[IMP] web: extra comments to explain commit 57b4860

Added some cryptic comments so we remember a bit
why we have a complicated dance with on_close.
Basically we do not want to reload the
original form view until the last popup is closed,
in the case where several wizard (steps) are opened
one after the other.
[FIX] payment_paypal: avoid json decode error

with post.pop('custom', '{}'), if the key 'custom' is not there, it will return '{}', but if the key is there, but the value is equivalent to False, the json decode will fail.
[FIX] mrp: do not reset back stock moves to confirm

For instance, setting a BOM Phantom with:
Finished product: stockable, MTO Manufacture
Components: stockable, MTS, Buy. Inventory set to 1000
Stock moves of components are directly set to assigned once the procurement confirmed thanks to JIT
The stock moves should not be set back to confirmed after they have been assigned
[MERGE] forward port of branch 7.0 up to 7307227
[IMP] crm_partner_assign: remove inexistant onchange

This field is readonly so a onchange is useless anyway (opw 612593)
[FIX] stock: on partial picking, do no open a new window action if not needed

This is related to rev. dd4d72d

Not opening a new window action allows to keep the current list of stock picking being threated, and to use the next an previous arrow of the forom view of the web client.
[MERGE] forward port of branch 7.0 up to 5872c24
[FIX] document: display Attachment(s) menu only on form view

The attachment menu (list and add) has no effect in tree view (not supporting multi-items upload and display), the menu should then only be displayed in these view (opw 612534)
[FIX] sale: keep page when confirming a sale order

To keep the pager and view changer after confirmation of a sale order, do not reload the view (quotation and sale order view are the same anyway)
Fixes #250
[MERGE] forward port of branch 7.0 up to 59b76ee
[FIX] tools,mail: improve parsing of references from rev. 0bee015dd67cb809fd235215b43d331074824e42

Backport of 8.0 fix was not enough for 7.0, because it still fails for the legacy reference match (model+res_id), which is not used in 8.0
[FIX] mail: translate tracked fields name in chatter

Status tracking messages are not translated into user's language while updating any document with tracked fields (opw 612847)
[FIX] web: do not allow to access a database if not matching db-filter
[FIX] stock: show the UoS quantity on picking lines

The pickings already show the UoS, but not the associated quantity, which makes it useless.
[IMP] css: width of readonly list view field

readonly float fields in list view were not correctly placed when the focus was on the line (seen espacially if field was large, e.g. nb_register on registration)
[FIX] ir_attachment: ignore if model uninstalled

if the model of an attachement no longer exists (the according module have been uninstalled, for instance), ignore the security check
[FIX] web: missing backport of rev df3c6b750249

[FIX] web: do not try to close a destroyed dialog. trigger "closing" signal on close by top-right "X" button