Gather all enchantment info into a single place

This also resolves several TODO notes about duplicate code and makes cPresetItem::ability an eEnchant

src/tools/SConscript

@@ -9,6 +9,7 @@ tools = Split("""
 	replay.cpp
 	../alchemy.cpp
 	../damage.cpp
+	../enchant.cpp
 	../location.cpp
 	../mathutil.cpp
 	../porting.cpp