Fix for Unity 2017.1 compatibility.

[LoganBooker]

• Supported language list field name was renamed in 2017.

[00christian00]

Hi, I tried compiling your version using the "fake" build system but the compiler still stays "stopped"

[CCludts]

@LoganBooker I managed to build using your fix, but get an error when I try to build inside Unity.

ArgumentNullException: Argument cannot be null.
Parameter name: source
System.Linq.Check.SourceAndPredicate (System.Object source, System.Object predicate)
System.Linq.Enumerable.Single[CustomScriptAssembly] (IEnumerable`1 source, System.Func`2 predicate)
UnityEditor.Scripting.ScriptCompilation.EditorCompilation.CompileScripts (EditorScriptCompilationOptions definesOptions, BuildTargetGroup platformGroup, BuildTarget platform) (at C:/buildslave/unity/build/Editor/Mono/Scripting/ScriptCompilation/EditorCompilation.cs:322)
UnityEditor.Scripting.ScriptCompilation.EditorCompilation.TickCompilationPipeline (EditorScriptCompilationOptions options, BuildTargetGroup platformGroup, BuildTarget platform) (at C:/buildslave/unity/build/Editor/Mono/Scripting/ScriptCompilation/EditorCompilation.cs:518)
UnityEditor.Scripting.ScriptCompilation.EditorCompilationInterface.TickCompilationPipeline (EditorScriptCompilationOptions options, BuildTargetGroup platformGroup, BuildTarget platform) (at C:/buildslave/unity/build/Editor/Mono/Scripting/ScriptCompilation/EditorCompilationInterface.cs:122)

Using Unity2017.1.1f1, windows 10.
I'm trying to build a single c# file in an empty project, so it shouldnt be anything related to extensions or things like that.

Any tips would be very much appreciated.

edit: After digging around for hours, it seems that Unity is complaining about multiple programming languages being used at the same time.
I found that the compilerPlugin.dll is using CustomCSharpLanguage, so this might be related...?
Still clueless on a fix though