- speed up QgsSpatialRefSys after migration to OGR C-API:

  - create and destroy OGRSpatialReferenceH in constructor/destructor
  - move the PROJ.4 strings to OGR instead of a member variable and keep
    track its validity in mIsValidFlag.
  This reduces the need to allocate/deallocate of OGR structures and PROJ.4
  parsing and thereby speeds it up quite a bit.  Especially when on-the-fly
  projection is in use.
- collect common code of createFromSrid, createFromEpsg and createFromSrsId
  in the new loadFromDb method

NOTE: invalid PROJ.4 strings are now lost, I hope that doesn't break
      anything.


git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@8263 c8812cc2-4d05-0410-92ff-de0c093fc19c

python/core/qgsspatialrefsys.sip

@@ -20,6 +20,8 @@ class QgsSpatialRefSys
 
         //! Default constructor
         QgsSpatialRefSys();
+
+        ~QgsSpatialRefSys();
 
         /*! 
          * Constructs a SRS object from a WKT string
@@ -34,7 +36,6 @@ class QgsSpatialRefSys
          */
         QgsSpatialRefSys(const long theId, SRS_TYPE theType=POSTGIS_SRID);
 
-
         // Misc helper functions -----------------------
 
         void createFromId(const long theId, SRS_TYPE theType=POSTGIS_SRID);