changing fieldnames from xmin to x_min

xmin and ymin are resevered fieldnames in Postgis, so better not
use these field names. Because this makes it impossible to create
a vector grid and transfer it to Postgis

python/plugins/fTools/tools/doVectorGrid.py

@@ -171,10 +171,10 @@ def compute( self, bound, xOffset, yOffset, polygon ):
         fieldCount = 1
 
         if polygon:
-            fields.append( QgsField("XMIN", QVariant.Double) )
-            fields.append( QgsField("XMAX", QVariant.Double) )
-            fields.append( QgsField("YMIN", QVariant.Double) )
-            fields.append( QgsField("YMAX", QVariant.Double) )
+            fields.append( QgsField("X_MIN", QVariant.Double) )
+            fields.append( QgsField("X_MAX", QVariant.Double) )
+            fields.append( QgsField("Y_MIN", QVariant.Double) )
+            fields.append( QgsField("Y_MAX", QVariant.Double) )
             fieldCount = 5
             check = QFile(self.shapefileName)
             if check.exists():