Initial version of JerryScript debugger (#1557)

The debugger supports setting breakpoints, execution control (step, next, continue)
and getting backtrace. The communication is WebSocket-based, so a browser can
communicate with JerryScript without any intermediate application.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com
JerryScript-DCO-1.0-Signed-off-by: Levente Orban orbanl@inf.u-szeged.hu

tests/debugger/do_step.js

@@ -0,0 +1,26 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+function f1()
+{
+  var i = 1;
+}
+
+function f2()
+{
+  var y = 2;
+}
+
+f1();
+f2();