add stl iterator interface in matrices. Cannoot add constructor...

add stl iterator interface in matrices. Cannoot add constructor Vector(begin,end) since it conflicts with Vector( val1, val2). Add also const methods for inverse and determinant. Rename enumeration variables to be consistent with ROOT naming conventions


git-svn-id: http://root.cern.ch/svn/root/trunk@13491 27541ba8-7e3a-0410-8455-c3a389f83636