refactored the maven plugin to use the vanilla K2JSCompiler directly and avoid using the K2JVMCompiler when generating JS code; also included a default LibrarySourceConfig which detects JS library code on the classpath which works nicer in maven/ant style worlds where dependencies tend to be specified rather than file paths to zip files

libraries/examples/js-example/src/main/kotlin/sample/Hello.kt

@@ -1,6 +1,11 @@
 package sample
 
-class Hello {
+public fun main(args: Array<String>): Unit {
+    val hello = Hello()
+    hello.doSomething()
+}
+
+public class Hello {
     var x = 0
 
     fun doSomething(): Unit {