inc/cpu_convolve.h:
- dropped debug_inplace (need to find other ways of having debug information)

inc/fft_utils.h:
- added parallel convolution through fftw3f_pthreads etc

src/CMakeLists.txt:
- linking against libfft3?* added

src/multiviewnative.cpp:
- implemented case distinction between single core and multi-core fft

tests/test_cpu_convolve.cpp:
- added test cases for by-depth convolution