Adapt to SG changes

src/Airports/GenAirports/build.hxx

@@ -32,6 +32,7 @@
 #include "global.hxx"
 #include "point2d.hxx"
 
+using std::string;
 
 // build 3d airport
 void build_airport( string airport_id, float alt_m,

src/Lib/Geometry/poly_support.cxx

@@ -54,6 +54,7 @@ extern "C" {
 using std::copy;
 using std::ostream_iterator;
 using std::sort;
+using std::string;
 using std::vector;
 
 #if 0 // unused

src/Lib/Geometry/util.cxx

@@ -18,6 +18,7 @@
 
 #define MP_STRETCH  (0.000001)
 
+using std::string;
 using std::vector;
 
 namespace tg {

src/Lib/Polygon/chop-bin.cxx

@@ -43,6 +43,8 @@
 #include "simple_clip.hxx"
 #include "chop.hxx"
 
+using std::string;
+
 static void clip_and_write_poly( string root, long int p_index,
                                  const string &poly_type,
                                  SGBucket b, const TGPolygon& shape,

src/Lib/Polygon/polygon.cxx

@@ -268,7 +268,7 @@ void TGPolygon::shift( double lon, double lat ) {
 
 
 // output
-void TGPolygon::write( const string& file ) const {
+void TGPolygon::write( const std::string& file ) const {
     FILE *fp = fopen( file.c_str(), "w" );
 
     fprintf(fp, "%ld\n", poly.size());
@@ -353,7 +353,7 @@ void tgPolygonFindSlivers( TGPolygon& in, poly_list& slivers )
 
 
 // output
-void TGPolygon::write_contour( const int contour, const string& file ) const {
+void TGPolygon::write_contour( const int contour, const std::string& file ) const {
     FILE *fp = fopen( file.c_str(), "w" );
     
     for ( int j = 0; j < (int)poly[contour].size(); ++j ) {

src/Prep/UserDef/tguserdef.cxx

@@ -22,6 +22,7 @@
 using std::vector;
 using std::cerr;
 using std::endl;
+using std::string;
 
 static string prog_name;
 static string work_dir = ".";