changing int in UInt, added a recursion in the subset method to avoid problems with Repeated vectors

in principle, should be add, but for importing is useful to have Zero

Commit done with Simone (contents not)

Enabled reducedToProc copy constructor.

Changed order of the members in EpetraVector for a cleaner initialization
of the class.

Enabled reducedToProc copy constructor.

  - Added new operators: (+=, -=, *=, /=) and (+ - * /) for Element By Element and Vector-Scalar operations (a total of 16 operators now!);
  - Added new logic operators: &&, ||, ! ;
  - Added new comparison operators: >=, <=, >, <, ==, != ;
  - Added Abs() method, and renamed scalar product to Dot() ;
  - Added ShowMe() method;
  - Added some doxygen (not finished yet) and reordered functions and methods;

Add small features to the EpetraVector

This method is still under testing, but seems working fine.

Added a new constructor for the class and re ordered the constructors (following the order in the .hpp)