mnmlstc-core conflicts with netgen

[barracuda156]

Error: Failed to activate mnmlstc-core: Image error: /opt/local/include/core/type_traits.hpp is being used by the active netgen port.  Please deactivate this port first, or use 'port -f activate mnmlstc-core' to force the activation.
    while executing
"throw registry::image-error $msg"
    ("foreach" body line 49)
    invoked from within
"foreach file $imagefiles {
                incr progress_step
                _progress update $progress_step $progress_total_steps
                se..."
    invoked from within
"registry::write {
            foreach file $imagefiles {
                incr progress_step
                _progress update $progress_step $progress_..."
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_devel_mnmlstc-core/mnmlstc-core/main.log for details.