-Rename class TFilePrefetch -> TFileCacheRead
-Rename class TTreeFilePrefetch -> TTreeCache
-Add new class TFileCacheWrite that implements automatic caching
 when writing network files. This class replaces the previous class TCache.
-old TCache class deleted.
-TFileCacheRead can read buffers from the wite cache in TFileCacheWrite.
-As a result TFile::UseCache is obsolete. The function is kept for
  backward compatibility.
-Remove references to TCache from TXMLFile, TSQLFile, TwebFile, TNetFile
-remove pointer TFile::fCache
-Add pointers TFile::fCacheRead and TFile::fCacheWrite
-Remove members fMaxCacheSize and fPageSize from TChain

NOTE that it is recommended to
  rm -f base/src/*.d base/src/*.o
  rm -f net/src/*.d  net/src/*.o
  rm -f tree/src/*.d tree/src/*.o


git-svn-id: http://root.cern.ch/svn/root/trunk@15572 27541ba8-7e3a-0410-8455-c3a389f83636