delay - delays a signal

delay output[b] input[bvpn] gain[bvpn] table[fvpn] length[vpn] pos[dpv] ;

delay output is equal to its input delayed by length and scaled by
gain.  The table should be a function (or a function index) whose
length is at least equal to the length argument.  An all- zero function
of length 39 milliseconds could be made with the command "gen 0 gen3
f2[39ms] 0 0;", for example.  Care should be exercised with this unit
generator, since the function may not contain two things at the same
time.  Therefore, instruments containing delays are not reentrant (they
can play only one note at a time).  Also, it will usually be necessary
to re-clear the delay table before each note begins (a macro to do this
might read:"#define Dnote(Time,Func)gen Time gen3 func 0 0; note Time").
