Merge branch 'master' of ssh://git.dcc.fc.up.pt/yap-6.3
Newest version of dbtries (several improvements and corrections of bugs) and the removal of a warning from flags
Merge branch 'master' of https://github.com/vscosta/yap-6.3
Merge branch 'master' of ssh://git.dcc.fc.up.pt/yap-6.3
Merge branch 'master' of https://github.com/vscosta/yap-6.3
with_mutex should succeed even in single-thread mode