logging
imported changes r2078, r2079
Merge branch 'working' into proverFeatures
Brought prover weighting into alignment with learner weighting
Refactored backtrace; added it to TracingDfs
Existential requirement for some file arguments
Integrated prover weighting scheme into main methods
Merge branch 'backtrace' into svn-r2079
resolved conflicts in merge with failFast
imported changes from svn r2125