Work to fix recovering sort status in headers view (fixes NB#58250).

Work to fix recovering sort status in headers view (fixes NB#58250).
* src/maemo/modest-platform.c:
        * Now it retrieves the current header view sort column,
          sort type, and in case of sorting flags, the flag we sort.
          This way, the dialog is prefilled with the current header
          view status.
* src/modest-widget-memory-priv.h:
        * Added the new kind of key "column-sort", that specified the
          model column used to sort in header view.
* src/modest-widget-memory.c:
        * Now save_settings_header_view and restore_settings_header_view
          store a global sort value. This is required for recovering the
          sort status in the compact view.

Other fixes:
* src/modest-ui-dimming-rules.c:
        * Condition for one or more attachments was wrong.

pmo-trunk-r2292