FEATURE: report all violations and not just the first one

[kshpytsya]

(Optionally) provide a way to report all violations, both of strictyaml's extra restrictions and those of schema, and not just the first one. I do realize that this may involve some major code overhaul but the best end user (i.e. the one that writes those yaml files) experience is the ultimate goal, isn't it?

[crdoconnor]

It is, yes. However, since I usually work through validation issues one by one just reporting the first error has worked okay for me.