Version 2.3.0

Version 2.2.0

Version 2.1.0

Version 2.0.2

Version 2.0.1

Version 2.0.0

Implement SSE detection in a more portable way

gcc versions older than 4.8 are still common in the field and
they do not support __builtin_cpu_supports() function. Switched
to old-style inline asm macro for some time.

Closes rtl-airband#1.