cmake: add a new GTK3.0 option

Thanks #micove for the patch
gtk2: use a pointer as argument instead of g variable

Easier and compliant with gtk3
gtk2: port gtk_combo_box to gtk_combo_box_text

The former was deprecated on gtk2.24 (and removed from gtk3)
gtk2: keyboard macro update
gtk2: GTK_OBJECT is useless
gtk2: use text rather than image

Require by GTK3
gtk2: GtkNotebookPage is useless

And not supported by gtk3
gtk3: GDK_WINDOW_XID was renamed

Well I guess. Not sure until I can test the behavior.
gtk3: gtk_hscale_new_with_range => gtk_scale_new_with_range
Merge pull request #385 from PCSX2/gtk3_compilation_fix

Gtk3 port (require wx built against GTK3).