accounting: prevent user from creating balance transaction while previous one is still beeing reindexed

Until now, it was only possible to define the ID on properties, then the
reference was guessed from the ID. We even had constraint to make sure
when we define a standard "foo" property that the ID was "foo_property".
Then the reference "foo" was guessed for the ID.

This is not user friendly, it is more logical to make the ID non editable
and guess it from the reference. Therefore now the developer could define
the reference, like "foo", and the corresponding ID will be automatically
set.

- run computation before trying to get results
- always defined a section, it is mandatory in UI so it should be in tests

A zindex of -1 breaks handsontable.

This reverts commit 514a5157.

This is very convenient when we use portal_templates.upgradeSite to
make sure some bt will always be installed with force=1. This is
usually used when we have a bt patching other bt.

Allows implementing user-based restrictions on classical ERP5-style
rendering.

This functional change should have been in a separate commit.

Commit accidentally reverted "IE use the latest rendering engine to
render the page". Reapply the change.

That template is only to be used for ERP5-style UI.

That template is only to be used for ERP5-style UI.

To encourage creation of alternative templates for web mode,
as this template must not be used outside of ERP5-style UI
(aka "ERP5 XHTML Style").

Sadly, we still implement our own escaping, as places escaping strings do
not know which connector will be used (proper escaping is
connector-dependent, because database-dependent).
Move this method in ZSQLCatalog to factorise code.

Disabled by default (configurable by user preference).

Also, reorganise erp5_auto_logout code:
- logout: Do not duplicate original code.
- twiddleAuthCookie: Simplify & factorise.
- setAuthCookie: Resync features with Cookie Crumbler's, and set http_only flag.
- ERP5Site_getMaxUserInactivityDuration: Cached access takes the same time as actual access (and access is surprisingly slow, actually), so do not cache.
- Base_getAutoLogoutSessionKey: New script, to factorise session key generation.

Editor Field does not escapes value, String Field does.

also :
* remove Accept-Encoding from Vary header, because Zope's response does not differ by Accept-Encoding request header.
* use getModificationDate() for modification time if available.