examples: Bug fix: import image/png explicitly (#500)

examples/blocks/blocks/gamescene.go

@@ -19,6 +19,7 @@ package blocks
 import (
 	"image/color"
 	_ "image/jpeg"
+	_ "image/png"
 	"math/rand"
 	"strconv"
 	"time"

examples/blocks/blocks/piece.go

@@ -18,6 +18,7 @@ package blocks
 
 import (
 	"image"
+	_ "image/png"
 
 	"github.com/hajimehoshi/ebiten"
 	"github.com/hajimehoshi/ebiten/ebitenutil"

examples/blocks/blocks/titlescene.go

@@ -18,6 +18,7 @@ package blocks
 
 import (
 	"image/color"
+	_ "image/png"
 
 	"github.com/hajimehoshi/ebiten"
 	"github.com/hajimehoshi/ebiten/ebitenutil"

examples/keyboard/main.go

@@ -17,6 +17,7 @@
 package main
 
 import (
+	_ "image/png"
 	"log"
 	"strconv"
 

examples/platformer/main.go

@@ -18,6 +18,7 @@ package main
 
 import (
 	"fmt"
+	_ "image/png"
 
 	"github.com/hajimehoshi/ebiten"
 	"github.com/hajimehoshi/ebiten/ebitenutil"

examples/ui/main.go

@@ -19,6 +19,7 @@ package main
 import (
 	"image"
 	"image/color"
+	_ "image/png"
 	"log"
 	"strings"