Clean up includes and include guards.

According to the C standard all preprocessor definitions starting
with an underscore are reserved for standard and implementation use,
so don't use those. Also, sort and unique include directives.

src/config.h.in

@@ -1,5 +1,5 @@
-#ifndef __CONFIG_H
-#define __CONFIG_H
+#ifndef SOLVESPACE_CONFIG_H
+#define SOLVESPACE_CONFIG_H
 
 #define PACKAGE_VERSION "@solvespace_VERSION_MAJOR@.@solvespace_VERSION_MINOR@~@solvespace_GIT_HASH@"
 

src/dsc.h

@@ -4,8 +4,8 @@
 //
 // Copyright 2008-2013 Jonathan Westhues.
 //-----------------------------------------------------------------------------
-#ifndef __DSC_H
-#define __DSC_H
+#ifndef SOLVESPACE_DSC_H
+#define SOLVESPACE_DSC_H
 
 #include "solvespace.h"
 

src/expr.h

@@ -4,8 +4,8 @@
 //
 // Copyright 2008-2013 Jonathan Westhues.
 //-----------------------------------------------------------------------------
-#ifndef __EXPR_H
-#define __EXPR_H
+#ifndef SOLVESPACE_EXPR_H
+#define SOLVESPACE_EXPR_H
 
 class Expr {
 public:

src/polygon.h

@@ -5,8 +5,8 @@
 // Copyright 2008-2013 Jonathan Westhues.
 //-----------------------------------------------------------------------------
 
-#ifndef __POLYGON_H
-#define __POLYGON_H
+#ifndef SOLVESPACE_POLYGON_H
+#define SOLVESPACE_POLYGON_H
 
 class SPointList;
 class SPolygon;

src/sketch.h

@@ -5,8 +5,8 @@
 // Copyright 2008-2013 Jonathan Westhues.
 //-----------------------------------------------------------------------------
 
-#ifndef __SKETCH_H
-#define __SKETCH_H
+#ifndef SOLVESPACE_SKETCH_H
+#define SOLVESPACE_SKETCH_H
 
 class hGroup;
 class hRequest;

src/solvespace.h

@@ -4,32 +4,31 @@
 // Copyright 2008-2013 Jonathan Westhues.
 //-----------------------------------------------------------------------------
 
-#ifndef __SOLVESPACE_H
-#define __SOLVESPACE_H
+#ifndef SOLVESPACE_H
+#define SOLVESPACE_H
 
-#include <stdint.h>
-#include <stdlib.h>
 #include <ctype.h>
-#include <string.h>
-#include <stdio.h>
-#include <stddef.h>
-#include <stdarg.h>
-#include <setjmp.h>
+#include <limits.h>
 #include <math.h>
 #include <setjmp.h>
-#include <limits.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #include <algorithm>
+#include <chrono>
 #include <functional>
-#include <memory>
-#include <string>
 #include <locale>
-#include <vector>
+#include <map>
+#include <memory>
+#include <set>
+#include <sstream>
+#include <string>
 #include <unordered_map>
 #include <unordered_set>
-#include <map>
-#include <set>
-#include <chrono>
-#include <sstream>
+#include <vector>
 
 // We declare these in advance instead of simply using FT_Library
 // (defined as typedef FT_LibraryRec_* FT_Library) because including

src/srf/surface.h

@@ -7,8 +7,8 @@
 // Copyright 2008-2013 Jonathan Westhues.
 //-----------------------------------------------------------------------------
 
-#ifndef __SURFACE_H
-#define __SURFACE_H
+#ifndef SOLVESPACE_SURFACE_H
+#define SOLVESPACE_SURFACE_H
 
 // Utility functions, Bernstein polynomials of order 1-3 and their derivatives.
 double Bernstein(int k, int deg, double t);

src/ttf.h

@@ -6,8 +6,8 @@
 // Copyright 2016 whitequark, Peter Barfuss.
 //-----------------------------------------------------------------------------
 
-#ifndef __TTF_H
-#define __TTF_H
+#ifndef SOLVESPACE_TTF_H
+#define SOLVESPACE_TTF_H
 
 class TtfFont {
 public:

src/ui.h

@@ -5,8 +5,8 @@
 // Copyright 2008-2013 Jonathan Westhues.
 //-----------------------------------------------------------------------------
 
-#ifndef __UI_H
-#define __UI_H
+#ifndef SOLVESPACE_UI_H
+#define SOLVESPACE_UI_H
 
 class Locale {
 public: