Merged "Scripts" and "Prefabs" folders into "src"

Made a new "src" folder that will contain the source code files, like all the GDScript and scene files. Please read this for more details: https://www.gdquest.com/docs/guidelines/best-practices/godot-gdscript/

It made no sense to keep scenes separate from their scripts. More file organizing will follow soon.

src/Palette/PaletteButton.gd

@@ -0,0 +1,27 @@
+extends Button
+signal on_drop_data
+
+export var index := 0;
+export var color : Color = Color.white
+export var draggable := false
+
+var drag_preview_texture = preload("res://Assets/Graphics/Palette/swatch_drag_preview.png")
+
+
+func get_drag_data(_position):
+	var data = null
+	if draggable:
+		data = {source_index = index}
+		var drag_icon = TextureRect.new()
+		drag_icon.texture = drag_preview_texture
+		drag_icon.modulate = color
+		set_drag_preview(drag_icon)
+	return data
+
+
+func can_drop_data(_position, _data) -> bool:
+	return true
+
+
+func drop_data(_position, data) -> void:
+	emit_signal("on_drop_data", data.source_index, index)