Add some help

- "Structure" -> "Structures"

extract_values can be used to copy analytic (or para-analytic) data from an object to another.
format_field_name returns an analytic field's name from its slot, prefix and suffix.

Fixed a bug that could break views when using the oe_analytic div without any analytic field to place.

Para-analytic are created and named according to the structure but do not take analytic codes as values. Instead, they can be any kind of field.

The analytic_structure method analytic_fields_subview_get allow any model (not necessarily one that implements MetaAnalytic) to display the analytic fields of models that have subviews defined inside its views. It is still strongly recommended to use ir.ui.view records and the [type]_view_ref context key instead.

Structures can now be restricted to one company. Bound dimensions: added the code_ref_ids (and code_ref_module) options to generate external IDs for all analytic codes of the dimension.

get_dimensions returns a dictionary with the dimension ID as key and their ordering as value. It can be useful in order to find the field associated with a specific dimension (obtained by external ID or by another model's get_dimension)

get_structures simply returns the structure browse records directly.

Bound dimensions: fixed an issue with the initialisation of related fields. Can now define the analytic code field in data (XML or CSV) files. Fixed a bug with the name methods.

Analytic_fields_view_get now sets the invisible and required attributes in addition to their respective keys in the modifiers dictionary (elias front-end compatibility).

Added 'usable' field in analytic.code. Analytic fields now filter out the codes with usable=False rather than those with children. Added the rel_name and rel_usable options for bound dimensions.