Log Message:
Changes 3.1:
* Faster FFTW_ESTIMATE planner.
* New (faster) algorithm for REDFT00/RODFT00 (type-I DCT/DST) of odd size.
* "4-step" algorithm for faster FFTs of very large sizes (> 2^18).
* Faster in-place real-data DFTs (for R2HC and HC2R r2r formats).
* Faster in-place non-square transpositions (FFTW uses these internally
  for in-place FFTs, and you can also perform them explicitly using
  the guru interface).
* Faster prime-size DFTs: implemented Bluestein's algorithm, as well
  as a zero-padded Rader variant to limit recursive use of Rader's algorithm.
* SIMD support for split complex arrays.
* Much faster Altivec/VMX performance.
* New fftw_set_timelimit function to specify a (rough) upper bound to the
  planning time (does not affect ESTIMATE mode).
* Removed --enable-3dnow support; use --enable-k7 instead.
* FMA (fused multiply-add) version is now included in "standard" FFTW,
  and is enabled with --enable-fma (the default on PowerPC and Itanium).
* Automatic detection of native architecture flag for gcc.  New
  configure options: --enable-portable-binary and --with-gcc-arch=<arch>,
  for people distributing compiled binaries of FFTW (see manual).
* Automatic detection of Altivec under Linux with gcc 3.4 (so that
  same binary should work on both Altivec and non-Altivec PowerPCs).
* Compiler-specific tweaks/flags/workarounds for gcc 3.4, xlc, HP/UX,
  Solaris/Intel.
* Various documentation clarifications.
* 64-bit clean.  (Fixes a bug affecting the split guru planner on
  64-bit machines, reported by David Necas.)
* Fixed Debian bug no.259612: inadvertent use of SSE instructions on
  non-SSE machines (causing a crash) for --enable-sse binaries.
* Fixed bug that caused HC2R transforms to destroy the input in
  certain cases, even if the user specified FFTW_PRESERVE_INPUT.
* Fixed bug where wisdom would be lost under rare circumstances,
  causing excessive planning time.
* FAQ notes bug in gcc-3.4.[1-3] that causes FFTW to crash with SSE/SSE2.
* Fixed accidentally exported symbol that prohibited simultaneous
  linking to double/single multithreaded FFTW (thanks to Alessio Massaro).
* Support Win32 threads under MinGW (thanks to Alessio Massaro).