Fixed forms title and description translation for extra fields: strings are now passed to t() function before rendering.

Removed t() function in uc_extra_fields_pane_panes_edit. Variables don't need to be translated before editing.

Fixed #814724, #751898, #792502 by aluminium, jpstrikesback, tomi2846 and other minor fixes: fixed visibility of extra fields on order edit pages, added configuration page for extra panes titles and descriptions, fixed postgresql compatibility problem, other minor fixes (fields summary, improved interface).

by jhl.verona: Added new feature. Now "extra fields" forms can be themed overriding theme_uc_extra_fields_pane function.

Fixed bug #759208 reported by Eszee: now shipping tokens are displayed correctly in invoices and mails.