serreverse() on intmods

[Vasily Golyshev <golyshev@mccme.ru>]

Hi,

I seem to be in need of a version of serreverse() that would
accept intmods as coefficients. Doing  Mod(serreverse(lift(*)),p) is no
good
since serreverse on ints is much slower than it would be on intmods
because of the accumulation of magnitudes as the precision of the series
grows. Which would be the recommended way of writing that? Creating a new
function using recip in gen3.c as a template, maybe?

Vasily.