layers: Addition of source_line_info.py script to simplify codegen debugging

vk-layer-generate.py and vk_helper.py now use added source_line_info.py script to insert comments throughout generated code indicating where the code was generated from.
diff --git a/source_line_info.py b/source_line_info.py
new file mode 100755
index 0000000..0d6f07e
--- /dev/null
+++ b/source_line_info.py
@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2015 LunarG, Inc.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a
+# copy of this software and associated documentation files (the "Software"),
+# to deal in the Software without restriction, including without limitation
+# the rights to use, copy, modify, merge, publish, distribute, sublicense,
+# and/or sell copies of the Software, and to permit persons to whom the
+# Software is furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+# DEALINGS IN THE SOFTWARE.
+
+from inspect import currentframe, getframeinfo
+
+# This is a wrapper class for inspect module that returns a formatted line
+#  with details of the source file and line number of python code who called
+#  into this class. The result can them be added to codegen to simplify
+#  debug as it shows where code was generated from.
+class sourcelineinfo():
+    def __init__(self):
+        self.general_prefix = "// CODEGEN : "
+        self.file_prefix = "file "
+        self.line_prefix = "line #"
+        self.enabled = True
+
+    def get(self):
+        if self.enabled:
+            frameinfo = getframeinfo(currentframe().f_back)
+            return "%s%s%s %s%s" % (self.general_prefix, self.file_prefix, frameinfo.filename, self.line_prefix, frameinfo.lineno)
+        return ""