Added backtrace (bt) and up/down commands.
Allow specifying breakpoints in file:line format for future load()s.

Breakpoints are a small memory leak right now as there's no way to clear them.

Running jsexec with the -D argument will enter the debugger.  Inside the
debugger, there are the following commands:
"r"                runs the script
"clear"            clears any pending exceptions (mostly useless)
"break ###"        set a break at the specified line number
"e <statement>"    eval()uates <statement> in the current frame
"eval <statement>" also eval()s

This is a proof of concept right now since it's only in jsexec and the command
parser is a joke.  Eventually, this will also work for ;EXEC scripts in the
BBS and be even more awesome.  This should be enough to get mcmlxxix off my
back though.

MAX_POST_LEN.

This makes the previous change effectively useless except for using up
space on the hard drive, but is stops from malloc()ing a copy of the data
that is unusable.

solve all the problems involved in a file upload though, so don't get too
excited.

where the file would/could be left open if fdopen() failed.

Apparently, it IS defined on Linux and FreeBSD, but is not currently
defined on OpenBSD (but I bet it used to be!).  This should fix the strange
zip behaviour reported by khelair.

use lprintf(LOG_ERR,...) instead of fprintf(stderr,...) to report errors
opening or allocating memory for areas.bbs file.

similar to the FTP server (wait forever for all child threads to terminate).

active_clients (protected integer) could be 0 at the time of recycle because
there can be delay at the beginning of the FTP ctrl thread (e.g. looking up
filtered IPs/hostnames) before the active_clients is incremented which could
be during/after it was destroyed by the cleanup() function. Now tracking
number of threads using protected integer which increments immediately upon
child thread creation and is not destroyed until the main thread terminates.
There is currently *not* timeout while waiting for child threads to terminate
upon shutdown/recycle, so this could result in a hung server thread if a child
thread is indefinitely hung - consider using a timeout.

Using C99 types (e.g. uint8_t instead of uchar).

did not work (since rev 1.96, Tue Sep 27 09:36:26 2005):  after selecting such
an editor available to a user solely because of their user number, their editor
setting would automatically revert to 0 (none/internal editor) because the user
number used for the ARS check in getuserdat() was 0. Fixed by setting the
user->number value before calling chk_ar().