Workaround for #71.
Do the scalar multiplication in reciprocal manually.
genc.c: Handle foam like (AElt Char (Cast Arr (CCall Word ...))) correctly
(ie. insert a cast to char* before the array reference.
sal_fold: Add a useful method for accumulating over an array
(+)/[x for x in 1..10] will add numbers 1 to 10.
add missing #include