Merge ND-evaluator into master

...ression/verification/purescala/invalid/Existentials.scala

...gression/verification/purescala/invalid/ForallAssoc.scala

...egression/verification/purescala/valid/Existentials.scala

...regression/verification/purescala/valid/ForallAssoc.scala

...s/regression/verification/purescala/valid/Predicate.scala

src/test/scala/leon/integration/solvers/SolversSuite.scala

...test/scala/leon/regression/synthesis/SynthesisSuite.scala

...n/verification/purescala/PureScalaVerificationSuite.scala

testcases/synthesis/etienne-thesis/List/Split.scala