and add support for buf device in vvm.
and add the nodangle functor to clean up the local symbols generated by elaboration and other steps.
Thanks to Larry Doolittle <LRDoolittle@lbl.gov>. Add the LPM_MUX device, and integrate it with the ternary synthesis from Larry. Replace the lpm_mux generator in t-xnf.cc to use XNF EQU devices to put muxs into function units. Rewrite elaborate_net for the PETernary class to also use the LPM_MUX device.