ARM platform ports

[hawkw]

this is kind of a pie-in-the-sky project that we probably shouldn't start on until we finish up some currently in flight stuff, but it would be neat to port mnemOS to ARM platform(s), such as Cortex-A and Cortex-M.

since MnemOS is primarily intended for "building small computers", my preference would be to prioritize Cortex-A and try to get it to run on a Raspberry Pi or something. but, a Cortex-M port could also be potentially nice if anyone is interested in embedded mnemOS deployments.