New C++ class AppConfig for maintaining the config.ini

New helper function for generating a unified "generated by slic3r" header.

xs/xsp/typemap.xspt

@@ -191,6 +191,8 @@
 %typemap{ModelInstancePtrs*};
 %typemap{Ref<ModelInstancePtrs>}{simple};
 %typemap{Clone<ModelInstancePtrs>}{simple};
+%typemap{AppConfig*};
+%typemap{Ref<AppConfig>}{simple};
 %typemap{GLShader*};
 %typemap{Ref<GLShader>}{simple};
 %typemap{GLVolume*};