Currently the public folder has:
```
template_gaia_flora.xml
template_gaia_flora_bush.xml
template_gaia_flora_bush_berry.xml
template_gaia_flora_tree.xml
template_gaia_flora_tree_fruit.xml
```
The first one is meaningful and defines the `wood.tree` resource and the corresponding map colour, among other things; the third and fifth replace that with `food.fruit`; the second and fourth only define a footprint and are thus not really worth a separate template. The bush vs tree distinction is arbitrary (and varies between languages, cultures, and people); functionally there is no difference in game.
This patch changes it to a cleaner and clearer:
```
template_gaia_fruit.xml
template_gaia_tree.xml
```
Having one generic template corresponding to a resource subtype is also consistent with:
```
template_gaia_fish.xml
template_gaia_ruins.xml
template_gaia_treasure.xml
```
For the specific gaia/flora_*.xml templates:
* the parents are updated accordingly;
* <ResourceSupply/Amount> is inserted to those that didn't have it yet;
* unnecessary `Dead ` and ` Tree` are removed from specific name strings.
[EDIT] And removed the `ForestPlant` class, since it's not used in the public mod.