Python debugger source & display command (#1850)

Reworked source(src) command to display a given range of the code, defaults to 3.

Added display command which does the same as the source, except it displays the source code everytime a breakpoint is hit.

Made tests for display, extended tests for src.

JerryScript-DCO-1.0-Signed-off-by: Daniel Balla dballa@inf.u-szeged.hu

tests/debugger/do_display.js

@@ -0,0 +1,23 @@
+// 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 a() { print("hi"); }
+function b() { print("welcome"); }
+function c() { print("hello"); }
+function d() { print("goodbye"); }
+
+a();
+b();
+c();
+d();