add singularize/pluralize overlead without using obsolete plurality enum
add PR to release notes
mark Singularize/Pluralize with Plurality as obsolete
provide better name for new paramters for Singularize/Pluralize
update readme with new preferred Singularize/Pluralize API
Merge pull request #306 from mexx/singularize-pluralize-obsolete-plurality

add singularize/pluralize overload without using obsolete plurality enum