Require stdint and inttypes; remove most (but not all) of torint.h; use standard PRIuXX macros

We've been requiring stdint.h for a while now -- trunnel headers all use it, and so does some of the hs_*.c code.

Let's assume that we have the standard c99 headers, and use their definitions of the stuff that they define. It isn't 2003 any more :)