erp5_credential: Add link to login in ERP5 with Google Account and use zocial.min.css to display it nicely

erp5_xhtml_style: Add link to login in ERP5 with Google Account and use zocial.min.css to display it nicely

The resource-to-account relationship is intended to be declared by
predicates (which are used here), but should only be explicitely set on
movements when they *differ* from these rules, as special overrides.
So, setting default accounts on movement is unnecessary work:
- predicate lookup is expensive, and business-model-specific shortcuts may
  be available which such generic implementation cannot implement
- multiplying unneeded relationships increases category table size, which
  is generally detrimental to performances

just test for truth instead of checking in [list of false instance]

fix typos and remove unused variables.

Login_isPasswordValid is no longer used.

When reseting password through portal_password, we should check new
password comply with policy.

Because user is not logged in at this stage, we expose a new method
`PasswordTool.analyzePassword` that checks the password is valid for
this reset key.

This is a change in the API, previously only "messages id" were
returned. To make it easier to reuse analyzePassword in other contexts,
we now return the message directly.

isPasswordValid returns a boolean value, so we should check it's true
rather than <= 0

method signature should not contain self

If it is the case *and* the action script does not redirect, the password will be
in user's browser history.
There can be two different reasons to not redirect:
- not following the API (ie, intentionally not redirecting)
- letting an exception reach ZPublisher
Also, if the non-redirection causes an HTML page to be rendered, resources
loaded by that page will have a referrer containing the password, leaking it
to potentially foreign servers.

obj.convert(format="png") != obj.convert(format=u"png")

When checking constraints, ignore lines where the node is an acquired
organisation, we should only consider lines where node is an account.

erp5_travel_expense: Improve Front page and fix CSS on image modal

erp5_travel_expense: Router redirect to front page

erp5_travel_request: Add missing Preference PropertySheet