Feature/collages

[up-87]

Prerequisites checklist

• I have read the contributing guidelines.

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

• Documentation update
• Bug fix
• New feature
• Other, please explain:
• Collage code cleanup (can most likely still be improved by using php classes but this should be okay)
• renaming some collage styles (2+2 instead of 2x2 as x now always indicates pictures are reused - old name still works)
• added simple 2+1 style that is to be used with a frame that fills the open space.

What changes did you make? (Give an overview)

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