Rotate collage images and final collage if needed (Fix #156)

[andi34]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "x" next to an item)

• Bug fix, fixes Enhance collage display #156

Collage creation is setup for landscape images, if we're taking pictures in portrait mode the result doesn't look like expected. To fix that we'll have to rotate the subimages before the real collage creation starts.

Another issue is that some collage layouts are optimized for printing and not for displaying in the gallery. Depending on our subimages orientation we'll now rotate the final collage for a better gallery experience.

Collage subimages on
Our print api, especially with QR-Code, ist also expecting landscape images. Portrait pictures should be rotated before we're going through the printing process.

What changes did you make? (Give an overview)

• rotate subimages of collage if needed
• rotate final collage if needed
• always print landscape images, rotate image if needed
• crop subimages of collage by center on 2x4 collage with background

Is there anything you'd like reviewers to focus on?