[BM2SM request] Forcibly save sm files using UTF-8 encoding format

[sillybear]

No description provided.

[SaxxonPike]

@sillybear I like this suggestion. Stepmania supports reading these, yes?

[sillybear]

Yeah any version. Default BM2SM encoding uses ANSI right? I have to manually resave files using utf-8 via notepad to make those non-Roman and special characters display correctly.

[SaxxonPike]

According to StepmaniaSM.cs - the default encoding from the .NET StreamWriter is used. Which should already be UTF-8 according to this MSDN doc: https://docs.microsoft.com/en-us/dotnet/api/system.io.streamwriter?view=netframework-4.7.2

However! This does not write the byte order mark. Reading further in the MSDN documentation, we see this:
This behavior is different from the behavior provided by the encoding object in the Encoding.UTF8 property. To specify a BOM and determine whether an exception is thrown on invalid bytes, use a constructor that accepts an encoding object as a parameter, such as StreamWriter(String, Boolean, Encoding) or StreamWriter.

So, when we use StreamWriter, we should specify Encoding.UTF8 in the constructor. This looks like a simple change.