Reorganize

[SimonGuilloud]

Reafactor and reorganize files:

• Root project moved to lisa-sets
• Removed unused legacy files and tests
• Put all automation tools in the same place
• Generally flatten folder structure, when possible
• Clean some files and imports

[sankalpgambhir]

Most changes look good to me.

I would personally prefer lisa.mathematics over lisa.maths, but it's fine either way.

Can merge after the compilation is fixed.