#95 wrong page displayed in double page mode

[Benoit Pierre]

When:

• double page mode is enabled, with "Show only one image when appropriate" set to "Only for wide images" or "Always"
• the previous archive 2 last pages are: a wide image followed by a narrow image
• the "previous page" action is used on the first page of the current archive, triggering a switch to the previous archive

Then the penultimate (wide) image of the previous archive is displayed instead of the last page.