This update from Philippe rationalizes the treatment of array of chars and bytes.

They are now considered by default as an array of numbers.  However if
they are used with an operator== or an operator!= and if the second argument
is also a string, the strcmp function will be used.  In addition, a direct call
of the function strstr is allowed.   The checks and error messages have been
improved for both the operator and strstr.
This update also corrects the problem where an expression was drawn multiple
times when using a fixed length array in string comparaison.


git-svn-id: http://root.cern.ch/svn/root/trunk@3390 27541ba8-7e3a-0410-8455-c3a389f83636