Changes for AVX2 detection
Update README file
Reference for CPU ID register information and inputs
Experiment with cpuid assembly
Manual de-clobbering for ebx
Test solution for clang x86 build
Use int instead of uint32_t
Use inline assembly recommended by Intel website

Further information here:
https://software.intel.com/en-us/articles/how-to-detect-new-instruction-support-in-the-4th-generation-intel-core-processor-family
Add missing double quotes and short URL for documentation reference
Merge pull request #16 from steinwurf/AVX2-detection

Avx2 detection