Reduced the number of firewalls to 2.
Replaced 2nd altar with a timer altar that opens the gates for a few
seconds to destroy the generators then closes the gates.
Added spikes connected to the first timer altar to attempt to resolve a
random problem where the food would drop the wrong way if the moving
spikes happened to be down at the moment the first timer altar reset.
git-svn-id: svn://svn.code.sf.net/p/crossfire/code/trunk/maps@3356 282e977c-c81d-0410-88c4-b93c2d0d6712
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