Make cocos palm regrow coconuts.

This feature is optional, and can be turned off.

Existing cocos trees are converted.

tree_models.lua

@@ -88,8 +88,13 @@ moretrees.birch_model2={
 	thin_branches=true
 }
 
+-- Coconuts can't be generated as fruit, because there is no support for the
+-- special fruit trunks that allow coconuts to regrow at the correct position
+-- in the tree.
+-- So, a placeholder fruit trunk is spawned. An ABM will convert it to the final
+-- fruit trunk, and generate the actual coconuts.
 moretrees.palm_model={
-	axiom="FFcccccc&FFFFFddd[^&&&GR][^///&&&GR][^//////&&&GR][^***&&&GR]FA//A//A//A//A//A",
+	axiom="FFcccccc&FFFFFdddRA//A//A//A//A//A",
 	rules_a="[&fb&bbb[++f--&ffff&ff][--f++&ffff&ff]&ffff&bbbb&b]",
 	rules_b="f",
 	rules_c="/",
@@ -101,7 +106,7 @@ moretrees.palm_model={
 	random_level=0,
 	trunk_type="single",
 	thin_branches=true,
-	fruit="moretrees:coconut",
+	fruit="moretrees:palm_fruit_trunk_gen",
 	fruit_chance=0
 }