Add round pixels and orange theme

[marcpabst]

Not sure how useful this is, but I think it's quite nice for people using led matrices. It's minor changes, so I'm just leaving this here - if there's interest to merge, I'll go through the PR checklist.

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PR description

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[rfuest]

Not sure how useful this is, but I think it's quite nice for people using led matrices. It's minor changes, so I'm just leaving this here - if there's interest to merge, I'll go through the PR checklist.

It's a bit outside the original scope of the simulator, but it probably looks nice. And because it's a minor non breaking change I wouldn't mind merging it.

[eflukx]

Crashes when pixel shape set to Dot with a pixel_spacing >= 3

thread 'main' panicked at C:\Users\Rogier\.cargo\git\checkouts\simulator-13139e92aab9a159\8562508\src\output_image.rs:96:42:
range end index 416388 out of range for slice of length 416331