Added a tooltip overlay for the variable layer height edit tool.

Short methods of PrintState made inline.
Added layer height profile to a Model class.

xs/xsp/Print.xsp

@@ -3,7 +3,6 @@
 %{
 #include <xsinit.h>
 #include "libslic3r/Print.hpp"
-#include "libslic3r/Slicing.hpp"
 #include "libslic3r/PlaceholderParser.hpp"
 %}
 
@@ -121,6 +120,8 @@ _constant()
     void _infill();
     void _generate_support_material();
 
+    bool update_layer_height_profile();
+
     void adjust_layer_height_profile(coordf_t z, coordf_t layer_thickness_delta, coordf_t band_width, int action)
         %code%{ 
             THIS->update_layer_height_profile();