KPC v0.1.2

In this version: * The URL to the published paper is added to the DESCRIPTION. * The default choice of K for the K-nearest neighbor (K-NN) graph in the variable selection algorithm KFOCI() is changed to 0.05n. More details of our suggestions on the choice of K are added to the documentation. * KFOCI() and KPCRKHS_VS() will run in parallel by default.