Add new package "minuit2"

The new package consists of two parts:
  -the base minuit2 package (ROOT independent) in its own tar file
  -the ROOT dependent classes T****.cxx
We expect to change the base tar file to expand it as normal classes
in a Minuit2 namespace.

To activate the minuit2 option, add to your configure
  --enable-minuit2
This craetes two libraries
  -libMinuit2.so
  -libminuitbase.a  (an archive lib with only the base classes)

In tutorials, 3 new tutorials are introduced comparing the performance
of TMinuit, TFumili with the new package.


git-svn-id: http://root.cern.ch/svn/root/trunk@13031 27541ba8-7e3a-0410-8455-c3a389f83636