Remove brand_code, model_bits and model_code fields, add a new brand sub-struct.
There fields were complicated to manage, adding complex functions to make it work.
amd_bits_t and intel_bits_t enums were truncated, I had to replace them with #define in 2e01aa0303.
Some of these #define were conflicting with other C headers (ctype.h on OpenBSD, corecrt_wctype.h on Windows), that is why I wanted to get rid of it.
I updated some CPU codenames meanwhile for more consistency.
Fix#212.