Make script launcher aware of custom scripts, minor correction is core env

compiler/testData/script/fib_std.kts

@@ -0,0 +1,10 @@
+// Expecting two string parameters
+
+fun fib(n: Int): Int {
+    val v = if(n < 2) 1 else fib(n-1) + fib(n-2)
+    System.out.println("fib($n)=$v")
+    return v
+}
+
+System.out.println("num: ${args[0]} (${args[1]})")
+val result = fib(java.lang.Integer.parseInt(args[0]))