Update version in Doxygen documentation

Doxyfile

@@ -38,7 +38,7 @@ PROJECT_NAME           = "OPAL (Object Oriented Parallel Accelerator Library)"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = "2.0.0"
+PROJECT_NUMBER         = "2.5"
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
@@ -2328,4 +2328,4 @@ GENERATE_LEGEND        = YES
 # The default value is: YES.
 # This tag requires that the tag HAVE_DOT is set to YES.
 
-DOT_CLEANUP            = YES
\ No newline at end of file
+DOT_CLEANUP            = YES