stronger separation between xeon and xeon phi code
moved primitive.h
xeonphi code does not include any file from xeon folder anymore
reporting error if called query function not supported
no longer generating fallback SSE and AVX code for intersector8 and intersector16
Release mode no longer compiler with debug symbols, added support for RelWithDebInfo
separated accel, accelset, and accelinstance, cleanups of symbol definition and declaration
cleanups in accel and accelset