[Insight-developers] USE_FFTWF and USE_FFTWD and Exlicit Instantiation

[Kent Williams]

Sorry about this problem -- It passed local regression tests, but we 
don't build the double-precision FFTW by default, so I missed the 
problems in the double precision version of the proxy class. Thanks for 
fixing it Luis.

The only way I know of to always test this code is to always build both 
single and double precision FFTW libraries on the testing machines.  
This isn't a big deal, since FFTW changes only once in a great while.