abc_cpp now checks the domain of the function.
New arguments parscale and fnscale added (see stats::optim)
New print and plot method for abc_answer class object.
Added a NEWS.md file to track changes to the package.
New function abc_cpp written with Rcpp (roughly 50%-100% faster than abc_optim).
Both abc_cpp and abc_optim return objects of class abc_answer.
Objects of class abc_answer return the trace of the global optimums.