Enabling this feature causes the node's temp directory to be cleared before
running the external program and causes the drop file(s) to be created-in and
read back from (when appropriate) the node's temp directory.

Creating drop files in a node's temp directory eliminates the possiblity of
an external program (e.g. door game) accidentally reading the wrong drop
file (e.g. wrong-cased name or a stale file of a different type).

Note: Synchronet/XSDK doors *always* read their drop file (xtrn.dat) from the
node directory, so don't try to use this option with those doors. Only doors
where you can configure the drop file path or specify on the command-line
(e.g. %g for the temp dir or %f for the fullpath of the drop file) should
potentially use this new feature.