Rename the raw memory access operators

For clarity, but really to avoid the clash with the internal
raw-vec-{ref,set!} operators.
Fix ARM
Fix remote bootstrapping
Remove the splitasm option

My slug died a long time ago, so support for machines with less that 64MB
of RAM seems unnecessary.   I remember when 64MB was a staggering
amount.
Move the buffer code from util.pco to driver.pco
Put the expanded no-interp form at the start of the program

They need to go at a defined point, and they can't go at the end
(becuase io.pco needs raw-stdout etc.), so put them at the start.