increate gc header alignment size
add pic_list_ref and pic_list_tail
add pic_append
impl list-ref and list-tail as C functions
replace length/reverse/append impls with c functions
replace list impl by scheme with impl by C
replace cxxr and list? impls by scheme with ones by C
replace list-set! impl with C impl
reduce exports
native implmentation of map
native implementatino of for-each