Add support for debugging templates loaded from the disk. This feature is a backport of an old patch done on a previous version of RazorEngine that was never integrated into the trunk (See https://razorengine.codeplex.com/SourceControl/list/patches  9279 and 9277)
Merge debugging support for templates on disk

Merge commit '83ae2e219dfc7fffb39a95b2f82c4425c5e511a0'