correct bug when writing if(..) a(i) = .. else 0

src/main/scala/leon/ArrayTransformation.scala

src/main/scala/leon/FairZ3Solver.scala

src/main/scala/leon/ImperativeCodeElimination.scala

src/main/scala/leon/plugin/CodeExtraction.scala

src/main/scala/leon/purescala/Definitions.scala

src/main/scala/leon/purescala/PrettyPrinter.scala

src/main/scala/leon/purescala/Trees.scala

src/main/scala/leon/purescala/TypeTrees.scala

testcases/regression/error/Array3.scala