Chrono clone fix

Fix nil index error in makeParadoxClone

I'm not sure how/why it happened, but while testing the 1.3.2 beta cut I got a nil index error in makeParadoxClone() while try to index on getInven("INVEN"). My character did have an inventory, so this seems strange. Anyway, it makes sense to check whether INVEN exists before trying to skip it.

Now, the function checks whether INVEN exists before adding it to the alt_nodes table.

This should be pushed to 1.3.2.