gr math simplification:
Replaces gr_gcd, gr_isnan, and gr_signbit one-time instances with boot math calls.No point in wrapping these utility math functions into gnuradio when they are1) provided by boost2) only called once
Removes gr_math.cc, and configure checks for isnan.
Initial checkin for VOLK - Vector-Optimized Library of Kernels. This is a new SIMD library.
It currently stands by itself under the GNU Radio tree and can be used separately. We will integrate the build process into GNU Raio and start building off of its functionality over time.