added file comment headers to express that this is now derived work and not the original Apple source code
The original Apple comment headers with (c) and license info are retained

added plan class creation method that allows to set flags to direct code generation
currently limited to select among 4 methods to compute twiddle factors:
-native_sin,native_cos function
-sincos() function
-set of two LUTs in global memory
-Taylor series approx via a smaller LUT in shared memory

experimental: -added alternative method for twiddle factor calc, using a smaller LUT (256 * float2 )
               via Taylor series to 3rd order, seems to be almost as accurate as method with 2 bigger LUTs, but faster.
              -improved method w/ 2 bigger LUTs to use LUTs of float2
              -improved method using slow sin/cos functions (now uses sincos combined function), still slow
              - preparaed plan struct to have method switchable at plan creation time.

              TODO: load smaller LUT for Taylor series approx into shared mem.

* Added dedicated Makefiles
* Added support for Mac OS 10.6
* TODO: proper Linux and Windows support
* Note: we need to add licensing headers!

* Based on Apple's OpenCL FFT implementation
* Derivative work done by Gaurav Khanna