ring-buffer with-memcpy macro unused yet

test-memcpy test funtion and macro will replace memcpy-params function

*memcpy-params more readable names for parameters

*memcpy-params	elmininated superfluous copy of ring-buffer-begin at top

ring-buffer with-memcpy externbal-buffer-begin parameter

external-buffer-begin increments
ring-buffer-begin modulo increments

test-memcpy test funtion and macro will replace memcpy-params function

ring-buffer with-memcpy (ring-buffer-begin-ptr external-buffer-begin-ptr size) part of closure
that gets called repeatedly to manage buffer wraparound
ring-buffer with-memcpy macro uses ensure-pairs macro to have a default value for externeal-buffer-begin-ptr

ring-buffer ring-buffer-begin-ptr part of ensure-pairs for readability

ring-buffer  with-memcpy impmenetend as binding struct

allows for default values for double lambda lists

ring-buffer  with-memcpy implemented as binding struct
allows for default values for double lambda lists
use of with-memcpy macro in make-ring-buffer

with-memcpy macro had redundant progn block removed
make-cffi-context and make-array-context return number of bytes processed