Added new dark wallpaper and fixed centering on all wallpapers

[gen1e]

Summary

• This is a…
  • [x] Bug fix
  • [x] Feature addition
  • [ ] Refactoring
  • [ ] Minor / simple change (like a typo)
  • [ ] Other
• Describe this change in 1-2 sentences: Added new dark wallpaper and re-centered other wallpapers.

Problem

• GitHub issue (optional): #117

Solution

SVGs were corrected

Action

Please let me know if they are magically off center again.

[jwflory]

@gen1e For convenience, could you drop rendered versions of the screenshots from your SVGs into this pull request?

[gen1e]

@jflory7 Sure here are all the updated ones