Added monster drops

Monsters can now be configured to drop items based on a resource (MonsterDrops.gd).
The usability is not the greatest, but that's due to not being able to export custom types. 
There were two possible approaches that I saw:
1. An `Array` holding dictionaries for each item that can be dropped along with the data needed for the drop behavior.
2.  Create a custom resource that would encapsulate all the data for the items that can be dropped from a monster: The item itself, min and max quantities, and the chance. 

I decided to go with the first one.

ps: The items are _NOT_ being added to the player's inventory . This is just the functionality needed for the monsters to start dropping items.

Closes gdquest-demos#59

godot/combat/Rewards.gd

@@ -13,6 +13,7 @@ func initialize(battlers : Array):
 	$Panel.visible = false
 	party = []
 	experience_earned = 0
+	randomize()
 	for battler in battlers:
 		if not battler.party_member:
 			battler.stats.connect("health_depleted", self, "_add_reward", [battler])
@@ -21,7 +22,15 @@ func initialize(battlers : Array):
 
 func _add_reward(battler : Battler):
 	experience_earned += battler.stats.experience
-	# TODO add item drops
+	if battler.drops != null:
+		for drop in battler.drops:
+			if drop.chance < 1.0 and rand_range(0.0, 1.0) > drop.chance:
+				continue
+			var quantity : int = 1 if drop.max_quantity == 1 else rand_range(drop.min_quantity, drop.max_quantity) as int
+			drops.append({
+				'item': drop.item,
+				'quantity': quantity
+			})
 
 func _reward_to_battlers() -> Array:
 	"""
@@ -56,7 +65,7 @@ func on_battle_completed():
 		$Panel/Label.text = "%s Leveled Up to %d" % [battler.name, battler.stats.level + 1]
 		yield(get_tree().create_timer(2.0), "timeout")
 	for drop in drops:
-		$Panel/Label.text = "Found %s" % drop.name
+		$Panel/Label.text = "Found %s %s(s)" % [drop.quantity, drop.item.name]
 		yield(get_tree().create_timer(2.0), "timeout")
 	$Panel.visible = false
 

godot/combat/battlers/Battler.gd

@@ -7,6 +7,7 @@ export var template : Resource
 
 const DEFAULT_CHANCE = 0.75
 var stats : CharacterStats
+var drops
 onready var lifebar_anchor = $InterfaceAnchor
 onready var skin = $Skin
 onready var actions = $Actions
@@ -26,6 +27,9 @@ func _ready() -> void:
 
 	var _t = template as BattlerTemplate
 	actions.initialize(_t.skills)
+
+	drops = _t.drops.items if _t.drops != null else null
+
 	skin.add_child(_t.anim.instance())
 	if stats == null:
 		var starting_stats = _t.stats as CharacterStats

godot/combat/battlers/BattlerTemplate.gd

@@ -5,3 +5,4 @@ class_name BattlerTemplate
 export var anim : PackedScene
 export var stats : Resource
 export var skills : Array
+export var drops : Resource

godot/combat/battlers/enemies/MonsterDrops.gd

@@ -0,0 +1,20 @@
+extends Resource
+class_name MonsterDrops
+
+"""
+While we still can't export custom types, we'll have to use an Array of dictionaries
+Example:
+	{
+		'item': Sword.tres,
+		'min_quantity': 1,
+		'max_quantity': 1,
+		'chance': 0.5
+	}, {
+		'item': Potion.tres,
+		'min_quantity': 3,
+		'max_quantity': 20,
+		'chance': 0.25
+	}, 
+"""
+
+export var items : Array

godot/combat/battlers/enemies/porcupine/Porcupine.tres

@@ -0,0 +1,15 @@
+[gd_resource type="Resource" load_steps=5 format=2]
+
+[ext_resource path="res://animation/PorcupineAnim.tscn" type="PackedScene" id=1]
+[ext_resource path="res://combat/battlers/enemies/porcupine/PorcupineDrops.tres" type="Resource" id=2]
+[ext_resource path="res://combat/battlers/BattlerTemplate.gd" type="Script" id=3]
+[ext_resource path="res://combat/battlers/jobs/Porcupine.tres" type="Resource" id=4]
+
+[resource]
+
+script = ExtResource( 3 )
+anim = ExtResource( 1 )
+stats = ExtResource( 4 )
+skills = [  ]
+drops = ExtResource( 2 )
+

godot/combat/battlers/enemies/porcupine/PorcupineDrops.tres

@@ -0,0 +1,15 @@
+[gd_resource type="Resource" load_steps=3 format=2]
+
+[ext_resource path="res://items/Potion.tres" type="Resource" id=1]
+[ext_resource path="res://combat/battlers/enemies/MonsterDrops.gd" type="Script" id=2]
+
+[resource]
+
+script = ExtResource( 2 )
+items = [ {
+"chance": 0.75,
+"item": ExtResource( 1 ),
+"max_quantity": 4,
+"min_quantity": 2
+} ]
+

godot/combat/battlers/formations/PorcupineFormation001.tscn

@@ -3,8 +3,9 @@
 [ext_resource path="res://combat/battlers/Formation.gd" type="Script" id=1]
 [ext_resource path="res://combat/background/StonePlatform.tscn" type="PackedScene" id=2]
 [ext_resource path="res://combat/battlers/formations/FormationMember.tscn" type="PackedScene" id=3]
-[ext_resource path="res://combat/battlers/enemies/Porcupine.tres" type="Resource" id=4]
-[ext_resource path="res://combat/battlers/enemies/StrongerPorcupine.tres" type="Resource" id=5]
+[ext_resource path="res://combat/battlers/enemies/porcupine/Porcupine.tres" type="Resource" id=4]
+[ext_resource path="res://combat/battlers/enemies/porcupine/StrongerPorcupine.tres" type="Resource" id=5]
+
 
 [node name="Formation" type="Node"]
 script = ExtResource( 1 )