fix wield scale on giant tree fern leaves
use real function calls instead of the old string method where possible
(basically leaving only the old legacy mapgen calls still using the string method)
remove useless mention of last revision.
legacy stuff should always be marked as "Warning:"
and make warnings more consistent
print a final report of the number of actions and legacy mapgen hooks that were registered
don't register surface types if their nodes aren't defined.
don't execute abstract_dryplants.grow_grass with "short" grass as a "surface" node.
as short grass may not always be there.  will do it a more proper way later.
route most of the various recent print statements through plantslib:dbg()
(still defaults to false)
that wasn't a memory leak
the table falls out of context at the end of the loop anyway
so the GC will delete it when the loop ends. No reason to delete it manually.
use set_node(), not add_node()
don't use minetest.env:* method (deprecated), use minetest.* instead
fix wield scale of giant fern tree crown
don't use inventory/wield image on youngtrees:bamboo.
let the engine show the nodebox instead.
typo
roll "legacy" mapgen calls into a loop similar to the standard one, call them
"no air check" instead.  Adjust debug prints and summary accordingly.

This reduces the total number of mapgen hooks from 5 down to just 2.
Add slightly reduced and rewritten version of mushroom mod by Dan
Duncombe and I, with tweaks added to make mushrooms able to spawn on
woodsoils grass/dirt with leaves.

Rewrites are just to make the ABMs a little lighter-weight, but they should
still function the same as before.

This mod does not hook into the map generator.
discontinue the old non-farming junglegrass-based pie recipe.
same for mixed berry pies
Early exit from abstract_ferns.grow_giant_tree_fern

(very) small performance increase
Renamed "leave" to "leaf" where appropriate
Refactor abstract_ferns.grow_giant_tree_fern

Arguably more readable; definately more maintainable

Potentially slower but if it is the difference would be negligable