UTF BOM screws up language auto-detect

[mitchcapper]

I noticed when doing a grep on a project some resx files had proper highlighting and some did not. Renaming them to XML fixed this (as it used extension detection for lang I assume) but after some troubleshooting I found the same file with and without BOM would result in the problem (with BOM preventing the auto detection).

[rhysd]

Thank you for catching this. It looks a bug of built-in grep feature.