update logging and add pl splash as the main one

PluginLoader/Compiler/RoslynCompiler.cs

@@ -61,7 +61,7 @@ public class RoslynCompiler
                 {
                     var location = diagnostic.Location;
                     var source = this.source.FirstOrDefault(x => x.Tree == location.SourceTree);
-                    LogFile.WriteLine(
+                    LogFile.Log.Debug(
                         $"{diagnostic.Id}: {diagnostic.GetMessage()} in file:\n{source?.Name ?? "null"} ({location.GetLineSpan().StartLinePosition})");
                 }