Ported the cooling changes from @alexrj: Don't slow down the external

perimeters if not necessary, don't take the bridging time into account
when slowing down the print.

Removed Extruder & GCodeWriter Perl bindings.
Improved Extruder for constness.
Refactored GCode::m_elapsed_time to struct ElapsedTime.

xs/xsp/Extruder.xsp

@@ -1,52 +0,0 @@
-%module{Slic3r::XS};
-
-%{
-#include <xsinit.h>
-#include "libslic3r/Extruder.hpp"
-%}
-
-%name{Slic3r::Extruder} class Extruder {
-    Extruder(unsigned int id, StaticPrintConfig* config)
-        %code%{ RETVAL = new Extruder (id, dynamic_cast<GCodeConfig*>(config)); %};
-    ~Extruder();
-    void reset();
-    double extrude(double dE);
-    double retract(double length, double restart_extra);
-    double unretract();
-    double e_per_mm(double mm3_per_mm);
-    double extruded_volume();
-    double used_filament();
-    
-    unsigned int id()
-        %code%{ RETVAL = THIS->id; %};
-    
-    double E()
-        %code%{ RETVAL = THIS->E; %};
-    double set_E(double val)
-        %code%{ RETVAL = THIS->E = val; %};
-    double absolute_E()
-        %code%{ RETVAL = THIS->absolute_E; %};
-    double set_absolute_E(double val)
-        %code%{ RETVAL = THIS->absolute_E = val; %};
-    double retracted()
-        %code%{ RETVAL = THIS->retracted; %};
-    double set_retracted(double val)
-        %code%{ RETVAL = THIS->retracted = val; %};
-    double restart_extra()
-        %code%{ RETVAL = THIS->restart_extra; %};
-    double set_restart_extra(double val)
-        %code%{ RETVAL = THIS->restart_extra = val; %};
-    double e_per_mm3()
-        %code%{ RETVAL = THIS->e_per_mm3; %};
-    
-    double filament_diameter();
-    double filament_density();
-    double filament_cost();
-    double extrusion_multiplier();
-    double retract_length();
-    double retract_lift();
-    int retract_speed();
-    double retract_restart_extra();
-    double retract_length_toolchange();
-    double retract_restart_extra_toolchange();
-};

xs/xsp/GCodeWriter.xsp

@@ -1,64 +0,0 @@
-%module{Slic3r::XS};
-
-%{
-#include <xsinit.h>
-#include "libslic3r/GCodeWriter.hpp"
-%}
-
-%name{Slic3r::GCode::Writer} class GCodeWriter {
-    GCodeWriter();
-    ~GCodeWriter();
-    
-    Ref<StaticPrintConfig> config()
-        %code%{ RETVAL = &THIS->config; %};
-    bool multiple_extruders()
-        %code{% RETVAL = THIS->multiple_extruders; %};
-    Ref<Extruder> extruder();
-    std::string extrusion_axis();
-    void apply_print_config(PrintConfig* print_config)
-        %code{% THIS->apply_print_config(*print_config); %};
-    void set_extruders(std::vector<unsigned int> extruder_ids);
-    std::string preamble();
-    std::string postamble();
-    std::string set_temperature(unsigned int temperature, bool wait = false, int tool = -1);
-    std::string set_bed_temperature(unsigned int temperature, bool wait = false);
-    std::string set_fan(unsigned int speed, bool dont_save = false);
-    std::string set_acceleration(unsigned int acceleration);
-    std::string reset_e(bool force = false);
-    std::string update_progress(unsigned int num, unsigned int tot, bool allow_100 = false);
-    bool need_toolchange(unsigned int extruder_id);
-    std::string set_extruder(unsigned int extruder_id);
-    std::string toolchange(unsigned int extruder_id);
-    std::string set_speed(double F, std::string comment = std::string());
-    std::string travel_to_xy(Pointf* point, std::string comment = std::string())
-        %code{% RETVAL = THIS->travel_to_xy(*point, comment); %};
-    std::string travel_to_xyz(Pointf3* point, std::string comment = std::string())
-        %code{% RETVAL = THIS->travel_to_xyz(*point, comment); %};
-    std::string travel_to_z(double z, std::string comment = std::string());
-    bool will_move_z(double z);
-    std::string extrude_to_xy(Pointf* point, double dE, std::string comment = std::string())
-        %code{% RETVAL = THIS->extrude_to_xy(*point, dE, comment); %};
-    std::string extrude_to_xyz(Pointf3* point, double dE, std::string comment = std::string())
-        %code{% RETVAL = THIS->extrude_to_xyz(*point, dE, comment); %};
-    std::string retract();
-    std::string retract_for_toolchange();
-    std::string unretract();
-    std::string lift();
-    std::string unlift();
-    Clone<Pointf3> get_position() const;
-%{
-
-SV*
-GCodeWriter::extruders()
-    CODE:
-        AV* av = newAV();
-        av_fill(av, THIS->extruders.size()-1);
-        int i = 0;
-        for (const Extruder &extruder : THIS->extruders)
-            av_store(av, i++, perl_to_SV_ref(const_cast<Extruder&>(extruder)));
-        RETVAL = newRV_noinc((SV*)av);
-    OUTPUT:
-        RETVAL
-
-%}
-};

xs/xsp/my.map

@@ -138,10 +138,6 @@ Clone<Surface>             O_OBJECT_SLIC3R_T
 SurfaceCollection*         O_OBJECT_SLIC3R
 Ref<SurfaceCollection>     O_OBJECT_SLIC3R_T
 
-Extruder*                  O_OBJECT_SLIC3R
-Ref<Extruder>              O_OBJECT_SLIC3R_T
-Clone<Extruder>            O_OBJECT_SLIC3R_T
-
 Model*                     O_OBJECT_SLIC3R
 Ref<Model>                 O_OBJECT_SLIC3R_T
 Clone<Model>               O_OBJECT_SLIC3R_T
@@ -201,10 +197,6 @@ GCodeSender*               O_OBJECT_SLIC3R
 Ref<GCodeSender>           O_OBJECT_SLIC3R_T
 Clone<GCodeSender>         O_OBJECT_SLIC3R_T
 
-GCodeWriter*               O_OBJECT_SLIC3R
-Ref<GCodeWriter>           O_OBJECT_SLIC3R_T
-Clone<GCodeWriter>         O_OBJECT_SLIC3R_T
-
 BridgeDetector*            O_OBJECT_SLIC3R
 Ref<BridgeDetector>        O_OBJECT_SLIC3R_T
 Clone<BridgeDetector>      O_OBJECT_SLIC3R_T

xs/xsp/typemap.xspt

@@ -99,9 +99,6 @@
 %typemap{MotionPlanner*};
 %typemap{Ref<MotionPlanner>}{simple};
 %typemap{Clone<MotionPlanner>}{simple};
-%typemap{GCodeWriter*};
-%typemap{Ref<GCodeWriter>}{simple};
-%typemap{Clone<GCodeWriter>}{simple};
 %typemap{GCodeSender*};
 %typemap{Ref<GCodeSender>}{simple};
 %typemap{Clone<GCodeSender>}{simple};
@@ -169,9 +166,6 @@
 %typemap{Polygons*};
 %typemap{TriangleMesh*};
 %typemap{TriangleMeshPtrs};
-%typemap{Extruder*};
-%typemap{Ref<Extruder>}{simple};
-%typemap{Clone<Extruder>}{simple};
 %typemap{Model*};
 %typemap{Ref<Model>}{simple};
 %typemap{Clone<Model>}{simple};