add a pause/unpause for parsing so that we can safely start parsing something new then continue parsing something old
make Mission_text and Mission_text_raw only use the memory needed, and free it when it doesn't need to parse anymore
(should work ok with FRED2, but I wasn't able to test it)
that used to reside in hasn't been marked as empty. This leads to the node still appearing in fred
if the user tries to delete the "ghosted" jump node, fred crashes.
Goober5000