unified pffft.c and pffft_double.c, extracted pf_[avx_]double.h

* unification: target is one single implementation template pffft_impl.h
and include it from different .c compile units
having set required preprocessor definitions
* removed PFFFT_FLOAT

Signed-off-by: hayati ayguen <h_ayguen@web.de>
diff --git a/pffastconv.h b/pffastconv.h
index 6d74482..11e82f8 100644
--- a/pffastconv.h
+++ b/pffastconv.h
@@ -126,7 +126,7 @@
     PFFASTCONV_Setup structure can't be shared accross multiple filters
     or concurrent threads.
   */
-  PFFASTCONV_Setup * pffastconv_new_setup( const PFFFT_FLOAT * filterCoeffs, int filterLen, int * blockLen, int flags );
+  PFFASTCONV_Setup * pffastconv_new_setup( const float * filterCoeffs, int filterLen, int * blockLen, int flags );
 
   void pffastconv_destroy_setup(PFFASTCONV_Setup *);
 
@@ -155,7 +155,7 @@
      input[].
 
   */
-  int pffastconv_apply(PFFASTCONV_Setup * s, const PFFFT_FLOAT *input, int inputLen, PFFFT_FLOAT *output, int applyFlush);
+  int pffastconv_apply(PFFASTCONV_Setup * s, const float *input, int inputLen, float *output, int applyFlush);
 
   void *pffastconv_malloc(size_t nb_bytes);
   void pffastconv_free(void *);