Reinstall fftw into MPI category

- Minor Updates based on Achim's suggestions.

MPI/fftw/modulefile

@@ -6,7 +6,10 @@ module-license      "GPL; http://www.fftw.org/doc/License-and-Copyright.html"
 module-maintainer   "Spencer Bliven <spencer.bliven@psi.ch>"
 
 module-help         "
-FFTW is a C subroutine library for computing the discrete Fourier transform (DFT) in one or more dimensions, of arbitrary input size, and of both real and complex data (as well as of even/odd data, i.e. the discrete cosine/sine transforms or DCT/DST).
+FFTW is a C subroutine library for computing the discrete Fourier transform
+(DFT) in one or more dimensions, of arbitrary input size, and of both real and
+complex data (as well as of even/odd data, i.e. the discrete cosine/sine
+transforms or DCT/DST).
 "