ea_import: whitespace cleanup
ea_import: many2one referenced class must be define before referrer

It's just a swap of these two classes, same code. But we must define
the "ea_import.template" before the "unique.rule" model.
ea_impoort: lazily import py-modules referring to addons

These pythonic modules will not appear in the "addons" path until the
addon (openerp-wise) is fully installed. So, that command must be done
inside some function, rather than the module head.
ea_import: pythonic improvements

We shall not pass mutable objects as function default parameters,
not catch system exceptions.
ea_import: assert that functions are called with a single id in "ids"

They are not designed to handle more records (return value is single),
so guard against misuse.
ea_import: an index on ea_import.log->chain_id
ea_import: "gtk-execute" icon doesn't exist in v6.0