Remove compiler warnings about unused parameters (issue #307)

FL/Fl_File_Input.H

@@ -87,7 +87,7 @@ public:
     \deprecated Will be removed in FLTK 1.5.0 or higher.
     \todo Remove Fl_File_Input::errorcolor(Fl_Color) in FLTK 1.5.0 or higher.
     */
-  void          errorcolor(Fl_Color c) {}
+  void          errorcolor(Fl_Color c) {(void)c;}
 
   int   value(const char *str);
   int   value(const char *str, int len);

FL/Fl_Graphics_Driver.H

@@ -373,7 +373,7 @@ public:
   virtual void overlay_rect(int x, int y, int w , int h);
   virtual float override_scale();
   virtual void restore_scale(float);
-  virtual PangoFontDescription* pango_font_description(Fl_Font fnum) { return NULL; }
+  virtual PangoFontDescription* pango_font_description(Fl_Font) { return NULL; }
   virtual void antialias(int state);
   virtual int antialias();
 };

FL/Fl_Image.H

@@ -75,7 +75,7 @@ private:
   Fl_Image & operator=(const Fl_Image &);
   Fl_Image(const Fl_Image &);
   // Presently redefined in Fl_SVG_Image
-  virtual void cache_size_(int &width, int &height) {}
+  virtual void cache_size_(int &/*width*/, int &/*height*/) {}
 
 protected:
 

FL/Fl_Image_Surface.H

@@ -103,7 +103,7 @@ protected:
   int height;
   Fl_Offscreen offscreen;
   int external_offscreen;
-  Fl_Image_Surface_Driver(int w, int h, int high_res, Fl_Offscreen off) : Fl_Widget_Surface(NULL), width(w), height(h), offscreen(off) {external_offscreen = (off != 0);}
+  Fl_Image_Surface_Driver(int w, int h, int /*high_res*/, Fl_Offscreen off) : Fl_Widget_Surface(NULL), width(w), height(h), offscreen(off) {external_offscreen = (off != 0);}
   virtual ~Fl_Image_Surface_Driver() {}
   virtual void set_current() = 0;
   virtual void translate(int x, int y) = 0;

FL/Fl_Native_File_Chooser.H

@@ -187,25 +187,25 @@ protected:
   static char *strfree(char *val);
   static char *strnew(const char *val);
 public:
-  Fl_Native_File_Chooser_Driver(int val) {}
+  Fl_Native_File_Chooser_Driver(int) {}
   virtual ~Fl_Native_File_Chooser_Driver() {}
-  virtual void type(int t) {}
+  virtual void type(int) {}
   virtual int type() const  {return 0;}
-  virtual void options(int o) {}
+  virtual void options(int) {}
   virtual int options() const {return 0;}
   virtual int count() const {return 0;}
   virtual const char *filename() const  {return 0;}
-  virtual const char *filename(int i) const  {return 0;}
-  virtual void directory(const char *val)  {}
+  virtual const char *filename(int) const  {return 0;}
+  virtual void directory(const char *)  {}
   virtual const char *directory() const {return 0;}
-  virtual void title(const char *t) {}
+  virtual void title(const char *) {}
   virtual const char* title() const {return 0;}
   virtual const char *filter() const  {return 0;}
-  virtual void filter(const char *f) {}
+  virtual void filter(const char *) {}
   virtual int filters() const  {return 0;}
-  virtual void filter_value(int i)  {}
+  virtual void filter_value(int)  {}
   virtual int filter_value() const  {return 0;}
-  virtual void preset_file(const char*f)  {}
+  virtual void preset_file(const char*)  {}
   virtual const char* preset_file() const {return 0;}
   virtual const char *errmsg() const  {return 0;}
   virtual int show()  {return 1;}

FL/Fl_Table.H

@@ -323,11 +323,11 @@ protected:
     </tr>
     </table>
 
-    \p row and \p col will be set to the row and column number
-    of the cell being drawn. In the case of row headers, \p col will be \a 0.
-    In the case of column headers, \p row will be \a 0.
+    \p R and \p C will be set to the row and column number
+    of the cell being drawn. In the case of row headers, \p C will be \a 0.
+    In the case of column headers, \p R will be \a 0.
 
-    <tt>x/y/w/h</tt> will be the position and dimensions of where the cell
+    <tt>X/Y/W/H</tt> will be the position and dimensions of where the cell
     should be drawn.
 
     In the case of custom widgets, a minimal draw_cell() override might
@@ -384,7 +384,7 @@ protected:
    */
   virtual void draw_cell(TableContext context, int R=0, int C=0,
                          int X=0, int Y=0, int W=0, int H=0)
-  { }                                           // overridden by deriving class
+  { (void)context; (void)R; (void)C; (void)X; (void)Y; (void)W; (void)H;}                                           // overridden by deriving class
 
   long row_scroll_position(int row);            // find scroll position of row (in pixels)
   long col_scroll_position(int col);            // find scroll position of col (in pixels)