GNSS-SDR v0.0.8

This is a maintenance and bug fix release with no relevant new features with respect to v0.0.7. The main changes are:

• Fixed a bug that broke building when using latest VOLK release
• Updated PYBOMBS instructions
• Added Tests for FFT length
• Added Tests for CUDA-based tracking
• Added Tests for SIMD-based tracking
• Improved CUDA-based correlation.
• Updated documentation
• Fixed building in mips and powerpc architectures.
• gr-gn3s and gr-dbfcttc moved to its own repository.
• Improved package reproducibility
• VOLK_GNSSSDR: Fixed a bug in AVX2 puppet
• VOLK_GNSSSDR: can now be built using the C98 standard
• VOLK_GNSSSDR: Fixed a bug that broke building when linking to Boost in some configurations.
• VOLK_GNSSSDR: Added an option to trigger profiling at building time.
• VOLK_GNSSSDR: Fix the CMake-based check for posix_memalign.