Add ui element interface

.gitignore

@@ -1 +1,2 @@
 last_light
+last_light.exe

DESIGN.md

@@ -18,6 +18,7 @@
         - Fire
         - Cold
         - Necrotic
+        - Thunder
         - Acid
         - Poison
 - 9-level Dungeon

render/layers.go

@@ -37,6 +37,18 @@ func (l *layer) draw(s tcell.Screen) {
 	}
 }
 
+type unorderedDrawContainer struct {
+	id       uuid.UUID
+	contents []Drawable
+}
+
+func CreateUnorderedDrawContainer(contents []Drawable) unorderedDrawContainer {
+	return unorderedDrawContainer{
+		id:       uuid.New(),
+		contents: contents,
+	}
+}
+
 type layeredDrawContainer struct {
 	id     uuid.UUID
 	layers []*layer

ui/ui.go

@@ -0,0 +1,12 @@
+package ui
+
+import (
+	"mvvasilev/last_light/util"
+
+	"github.com/google/uuid"
+)
+
+type UIElement interface {
+	UniqueId() uuid.UUID
+	Position() util.Position
+}