Use ESSL 1.0 for EGLRenderer shaders

We still ostensibly support GLES 2.0 GPUs.

app/shaders/egl.vert

@@ -0,0 +1,8 @@
+attribute vec2 aPosition; // 2D: X,Y
+attribute vec2 aTexCoord;
+varying vec2 vTexCoord;
+
+void main() {
+    vTexCoord = aTexCoord;
+    gl_Position = vec4(aPosition, 0, 1);
+}