tools: fix project name on Windows

tools/level_editor/project.vala

@@ -223,6 +223,12 @@ end
 			return _platform;
 		}
 
+		public string name()
+		{
+			string sd = source_dir();
+			return sd.substring(sd.last_index_of_char(GLib.Path.DIR_SEPARATOR) + 1);
+		}
+
 		public bool path_is_within_dir(string path, string dir)
 		{
 			GLib.File file = GLib.File.new_for_path(path);

tools/level_editor/project_store.vala

@@ -67,7 +67,7 @@ namespace Crown
 				, Column.TYPE
 				, "<folder>"
 				, Column.SEGMENT
-				, segment(_project.source_dir())
+				, _project.name()
 				, -1
 				);