Add indication of auto-generation to generated bindings

[just-ero]

Description

This is mainly for the C# bindings; warnings are reported in the file due to style inconsistencies. Of course, we can't (or shouldn't) edit LiveSplitCore.cs directly. To suppress warnings in the file, I suggest adding something like this to the generated file:

//---------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by a tool.
//     livesplit-core v0.13.0
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//---------------------------------------------------------------------------

This is consistent with other .NET source code generators. The <auto-generated /> element suppresses all warnings.