Enhance collage display

[GeoffreyV]

Is your feature request related to a problem? Please describe.
When using collage and standalone picture, the collage display is 90° rotated

Describe the solution you'd like

• Rotate collage when displaying it if necessary (2x4 and 2x4BI for example)

• Not display twice the pictures for collage where some photos are duplicated (2x4 for instance)
  The collage is optimized for printing but not for display (small screen)

Describe alternatives you've considered

When using collage only (see #155), setting 90 to preview rotation is a workaround

[andi34]

Thanks for your suggestion, I'll try to find a solution

[andi34]

Please take a look at #163, it'll rotate the sub-pictures if needed and also rotate the final collage if needed.

[andi34]

Fixed by #163,
On 2x4 displaying the same 4 images twice is what we want (not changed).