Robot simulator: Sync with problem-specifications

[tasxatzial]

Closes #456

Complete re-write of tests. Took way longer than expected because I wasn't able to decide what's the most appropriate way to write them. So, i just picked the one that looked best to me.

This PR is not expected to break existing solutions

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[tasxatzial]

Don't approve yet. Just open. There's an error i have to fix.

Edit: Not sure why the tests did not fail though.

[tasxatzial]

Ok, fixed, it was a just a deftest declared twice.

Edit: I'll push when the PR is re opened.