Overload deprecated Base versions of functions (#5)

Author: ararslan

src/AbstractFFTs.jl

@@ -7,11 +7,18 @@ using Base.LinAlg: BlasReal
 import Base: show, summary, size, ndims, length, eltype,
              *, A_mul_B!, inv, \, A_ldiv_B!
 
-if !isdefined(Base, :DFT)
-    export fft, ifft, bfft, fft!, ifft!, bfft!,
-           plan_fft, plan_ifft, plan_bfft, plan_fft!, plan_ifft!, plan_bfft!,
-           rfft, irfft, brfft, plan_rfft, plan_irfft, plan_brfft,
-           fftshift, ifftshift
+if VERSION >= v"0.7.0-DEV.602"
+    if isdefined(Base, :DFT)
+        import Base: fft, ifft, bfft, fft!, ifft!, bfft!,
+                     plan_fft, plan_ifft, plan_bfft, plan_fft!, plan_ifft!, plan_bfft!,
+                     rfft, irfft, brfft, plan_rfft, plan_irfft, plan_brfft,
+                     fftshift, ifftshift
+    else
+        export fft, ifft, bfft, fft!, ifft!, bfft!,
+               plan_fft, plan_ifft, plan_bfft, plan_fft!, plan_ifft!, plan_bfft!,
+               rfft, irfft, brfft, plan_rfft, plan_irfft, plan_brfft,
+               fftshift, ifftshift
+    end
 end