FEAT: support for read/write access on CPU's general-purpose registers added to Red/System.

Usage:
    system/cpu/<reg>
    system/cpu/<reg>: <value>

<reg>:
    - IA-32: eax, ebx, ecx, edx, esp, ebp, esi, edi
    - ARM: r0 - r15
Merge branch 'freebsd' of github.com:red/red into freebsd