2.3.0 Deprecate ugly methods, update sampleMultiple() behaviour (breaking)

• There were uncertainties with upTo() method because from its name it wasn't clear if 0 was included. From now on use only integer(min, max) instead, it's more explicit
• sampleMultiple(Collection) was returning empty collections as one of the possibilities. But it wasn't convenient, if user wants empty collections then he should be explicit about that. The method now returns collections with at least 1 element.