Used variable in Rcpp distance functions

Issue #66 resolved
Jason Vander Heiden
created an issue
RcppDistance.cpp: In function ‘Rcpp::NumericMatrix subPairwiseDistRcpp(Rcpp::StringVector, Rcpp::NumericVector, Rcpp::NumericMatrix)’:
RcppDistance.cpp:266:12: warning: unused variable ‘distance’ [-Wunused-variable]
     double distance;