The great 'long int' purge of 2023 part 1

At one time, Synchronet was a 16-bit DOS project, plagued by the 16-bit [u]int, so long's were used everywhere > 16-bits were known to be needed/wanted (This is before the days of the standard sized types from stdint.h), and they've persisted.

But '[u]long int' is 64-bits on *nix 64-bit builds, 32-bits everywhere else (even 64-bit Windows builds if/when we ever get around to that), so this could lead to insidious bugs that would only show up on one flavor or the other. Since [u]int is 32-bits on everything we currently support, we'll use that instead of [u]long.

This "part 1" because I'm sure there's going to be warnings and errors from the GCC/Clang builds as a result, which I'll get to next.