Because we forgot to increment the TView class number when moving to double precision,

the only way to recognize the old versions is to test the file version in Streamer.
This change is necessary to real old canvases in Root files generated
before version 2.24/05.


git-svn-id: http://root.cern.ch/svn/root/trunk@496 27541ba8-7e3a-0410-8455-c3a389f83636