This is preferable to using time_diff() to compare two timevals, because
time_diff() gives its result as a 'double' which only has 53 bits of
precision.
Also switch a couple of places from using time_diff() to using
this function.
If we immediately handle timers that have already expired, there doesn't
seem to be a compelling reason to add 100ms to the expiry of unexpired timers.
This function never worked - function_timer() was creating a string but then
never throwing it away and returning a part of the argument instead, which
then caused a crash because it couldn't be freed later in the expression
parsing.
git-svn-id: svn://svn.code.sf.net/p/bitchx/code/trunk@472 13b04d17-f746-0410-82c6-800466cd88b0
