mip_mrsort_veto: remove debugginf trace
pymcda: generate_random_veto_thresholds: add veto_interval parameter

It allows to specify in which interval the veto threshold should be
set.
apps: add test_mip_mrsort_veto
pymcda: electre_tri: add count_veto_pessimist() method
apps: test_mip_mrsort_veto: count number of veto effects
test_mip_mrsort_veto: add confusion matrices
apps: test_veto: print number of veto effects
count_veto_effects: add small script to count number of veto effects
generate: fix generate_random_veto_thresholds()
generate: add possibility to generate veto weights
test_mip_mrsort_veto: give the possibility to learn model with/without veto
types: improve from_xmcda() methods

If an invalid tag is given to the from_xmcda() method, then search for
the tag in the xml structure.
types: allow to save in xmcda with another tag id
electre_tri: simplify the xmcda decoding
test_mcda: add test of MRSort xmcda encoding
electre_tri: fix computation of veto effect for binary vetoes
generate: add generate_random_veto_thresholds_abs/prop()
count_veto_effects: adaptation for the new veto generation rule
mip_mrsort_veto: add the possibility to learn only veto profiles
apps: test_veto: add possibility to learn only the veto profiles