add regression to the top level and adapt run-tests script

regression/valid/Nested12.scala

regression/valid/Nested13.scala

regression/valid/Nested14.scala

regression/valid/Nested2.scala

regression/valid/Nested3.scala

regression/valid/Nested4.scala

regression/valid/Nested5.scala

regression/valid/Nested6.scala

regression/valid/Nested7.scala

regression/valid/Nested8.scala

regression/valid/Nested9.scala

regression/valid/NestedVar.scala

regression/valid/Unit1.scala

regression/valid/Unit2.scala

regression/valid/While1.scala

regression/valid/While2.scala

regression/valid/While3.scala

run-tests.sh