Enabling multibyte support on `lengthBetween` validation rule.
Enabling multibyte support on `lengthBetween` validation rule.

Refs #270.

datachand/lithium,qoqa/lithium,whowgames/lithium,wbeater/lithium,datachand/lithium,whowgames/lithium,jails/lithium,muyehub/lithium,UnionOfRAD/lithium,mehlah/lithium,wbeater/lithium,qoqa/lithium,m4rcsch/lithium-core-library,SensCritique/lithium,davidpersson/lithium,mehlah/lithium,muyehub/lithium,jails/lithium,UnionOfRAD/lithium,graphis/lithium,graphis/lithium,m4rcsch/lithium-core-library,SensCritique/lithium,pixelcog/lithium,davidpersson/lithium,pixelcog/lithium