Rename jet -> kotlin in frontend: PSI

org.jetbrains.jet.lang.psi -> org.jetbrains.kotlin.psi

idea/testData/findUsages/kotlin/findClassUsages/javaClassFunctionUsages2.0.kt

@@ -1,4 +1,4 @@
-// PSI_ELEMENT: org.jetbrains.jet.lang.psi.JetClass
+// PSI_ELEMENT: org.jetbrains.kotlin.psi.JetClass
 // OPTIONS: functionUsages
 trait X {
     val a: String
@@ -34,4 +34,4 @@ open class <caret>A: X {
     override fun foo(s: String) {
         println("!$s!")
     }
-}
+}