Update doorscan.js - fix "TypeError: argv[i].toLowerCase is not a function" when being called from webv4

amymore.

1) When a log file does not exist, mark it as having been parsed rather
   than retrying next time.
2) Keep track of the oldest since date and do not parse after it

Make the config command work... this should be added as an external, or
a menu option.

you last scanned.

of externals being ran.

Add comments explaining user settings.

Intended to run as a login event and as a bbs.exec_xtrn() wrapper, this
will track new doors, and doors which have had activity since you last
played.

To set up the login event:
SCFG -> External Programs -> Fixed Events -> Logon Event
	"*../xtrn/doorscan/doorscan.js scan"

The modification to exec/xtrn_sec.js:
At around line 136:
//bbs.exec_xtrn(xtrn_area.sec_list[xsec].prog_list[i].code);
try {
	load("../xtrn/doorscan/doorscan.js","run",xtrn_area.sec_list[xsec].prog_list[i].code);
}
catch(e) {
	log("Error running "+xtrn_area.sec_list[xsec].prog_list[i].code+" "+e);
}