[Insight-developers] add template parameters to optimizer base class

[brian avants]

hi everyone

itkCostFunction defines the following:

class ITK_EXPORT CostFunction:public Object
{
public:

< snip >

  /**  ParametersType typedef.
   *  It defines a position in the optimization search space. */
  typedef double                       ParametersValueType;
  typedef Array< ParametersValueType > ParametersType;

....

what we'd like to do is define ParametersValueType via a template parameter
such that we can use float type.

the motivation is to allow us to have Derivatives/Parameters that are
float deformation fields or float BSpline parameter images that are
then memory mapped to Parameter/DerivativeType arrays.

does anyone have any objection?   we'd have to make changes to all the
derived classes but these changes should be backward compatible
because the default template parameter for ParametersValueType would
be double ( as it currently is ).

brian