Ignore empty lines in source list files

[jrencz]

I suggest that empty lines should be ignored when <!-- include:js(list:vendorList) --> syntax is used.
At least the last empty line should since in many cases people set their IDEs/editors to add an empty line at the end of each saved file.

[jrencz]

now each empty line is turned info <script src=""></script> which is incorrect.