confine/sliver.lua:add_lslv_err() fix error member creation
confine/sliver.lua:cb2_set_slivers() fix non-exising uri_id
vct.conf.default: fixed ncurses-dev fo libncurses5-dev dependency, closes #204
vct: improve vct_build_sliver_exp_data()
vct: preliminary vct_build_sliver_template(), untested