Follow ups to the Ising cluster update PR

[ev-br]

• update the example/README
• add meson.build for the new Cython examples, consolidate setup.py files
• Add new examples to CI
  .
• Add an example of the structure from conformations (in a ipynb, simulation should accept a prepared lattice)

[ev-br]

@MoskalenkoRomanBorisovich would be nice to tackle the last bit, an example of an Ising simulation on a lattice from a short SAW conformation (no need to read it from a file, just provide the walk, plot it, construct the lattice and run your cluster simulation on it; then compare to the enumeration)

[ev-br]

Ok, the last remaining item is tracked at gh-16, so closing this in favor of that one