merged branch h2s/embed-error-line (PR #1140)

This PR was squashed before being merged into the master branch (closes #1140).

Discussion
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Fix for {% embed %} error line number bug

This deals with issue #958. I've gone into a lot of detail about the fix itself in the commit message for 12cc0a0, so I won't repeat any of that here. Take a look and let me know what you think!

Commits
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270b791 Fix for {% embed %} error line number bug