improve error messages (#1506)

- better inheritance of `Error` sub-classes
- mark parse error against source in CLI

closes #235
closes #348
closes #524
closes #1356
closes #1405

test/mocha/line-endings.js

@@ -50,7 +50,7 @@ describe("line-endings", function() {
         }
         var fail = function(e) {
             return e instanceof Uglify.JS_Parse_Error &&
-                e.message === "SyntaxError: Unexpected line terminator";
+                e.message === "Unexpected line terminator";
         }
         for (var i = 0; i < inputs.length; i++) {
             assert.throws(test(inputs[i]), fail);