This commit applies changes that enable
the use of the global controller
by default. Before, a NULL controller
indicated that the reader is parallel.
However, with this change, the Controller
is almost guaranteed to be non-NULL. To
determine whether the reader is running
serially or parallel, an additional helper
method was added which checks both if the
Controller is NULL and the total number of
processes associated with the controller.
Consequently, all conditional statements of
"if( this->Controller != NULL )" have been
updated to "if( this->IsParallel() )" which
implements the correct behavior.