add examples from lectures

lecture-02/Expr/Expr.hs

lecture-02/Expr/Expr2.hs

lecture-02/Expr/ListMonad.hs

lecture-02/Expr/MaybeMonad.hs

lecture-02/Expr/ReaderMonad.hs

lecture-02/Expr/ResMonad.hs

lecture-02/IMP/Absy.hs

lecture-02/IMP/Examples.hs

lecture-02/IMP/IMP.hs

lecture-02/Scala/State.scala

lecture-02/Scala/StateT.scala

lecture-02/Scala/build.sbt

lecture-02/Scala/project/build.properties

lecture-02/StateMonadT.hs

lecture-02/project/build.properties

lecture-03/Haskell/ConcExn.hs

lecture-03/Haskell/Robots3.hs

lecture-03/Haskell/RobotsEx1.hs

lecture-03/Haskell/RobotsEx2.hs

lecture-03/Haskell/RobotsEx3.hs