Workaround for bug with Mono's MSBuild and BaseIntermediateOutputPath

BaseIntermediateOutputPath seems to be empty by default. The workaround is to explicitly set it.

Also fixed passing char instead of char[] to String.Split. Why was this even working with Mono?

modules/mono/editor/GodotSharpTools/Build/BuildSystem.cs

@@ -257,7 +257,7 @@ namespace GodotSharpTools.Build
             if (null == Parameters)
                 throw new LoggerException("Log directory was not set.");
 
-            string[] parameters = Parameters.Split(';');
+            string[] parameters = Parameters.Split(new[] { ';' });
 
             string logDir = parameters[0];
 

modules/mono/editor/GodotSharpTools/Project/ProjectGenerator.cs

@@ -21,6 +21,7 @@ namespace GodotSharpTools.Project
             mainGroup.AddProperty("DocumentationFile", Path.Combine("$(OutputPath)", "$(AssemblyName).xml"));
             mainGroup.SetProperty("RootNamespace", "Godot");
             mainGroup.SetProperty("ProjectGuid", CoreApiProjectGuid);
+            mainGroup.SetProperty("BaseIntermediateOutputPath", "obj");
 
             GenAssemblyInfoFile(root, dir, CoreApiProjectName,
                                 new string[] { "[assembly: InternalsVisibleTo(\"" + EditorApiProjectName + "\")]" },
@@ -46,6 +47,7 @@ namespace GodotSharpTools.Project
             mainGroup.AddProperty("DocumentationFile", Path.Combine("$(OutputPath)", "$(AssemblyName).xml"));
             mainGroup.SetProperty("RootNamespace", "Godot");
             mainGroup.SetProperty("ProjectGuid", EditorApiProjectGuid);
+            mainGroup.SetProperty("BaseIntermediateOutputPath", "obj");
 
             GenAssemblyInfoFile(root, dir, EditorApiProjectName);