I took Leos code and mixed that into a new script addin for easier use. Thanks again Leo! o)
ConvertEx:
After installing the addin, you can use the provided button-menu or create a new button with the following command to remove UTF8-BOM from files:
ConvertEx REMOVEUTF8BOM DESELECT=success NODESELECT
ps: I played some more with powershell to get something more tiny for the UTF8-BOM removal, but I always ended up using an equal amount of code compared to the DO specific JScript, so there's no real benefit in a powershell version (unless you need to run that code outside of DO). The 3-liner powershell versions out there always seem to mess around with the line endings (adding additional linebreaks at the end e.g.), not an option if you ask me.