move shaders into .glsl files and add #include feature

data/shaders/equirect.glsl

@@ -0,0 +1,29 @@
+[[vertex]]
+#define PI 3.1415926535897932384626433832795
+#define TWO_PI 6.283185307179586476925286766559
+uniform mat4 mvp;
+in vec4 pos;
+in vec2 uvs;
+out vec2 uv;
+void main()
+{
+   uv = (vec2(1.0) - uvs + vec2(0.25,0.0)) * vec2(TWO_PI, PI);
+   gl_Position = mvp * vec4(pos.xyz, 1.0);
+}
+
+[[fragment]]
+uniform samplerCube tex;
+in highp vec2 uv;
+out mediump vec4 frag;
+void main()
+{
+   highp float anglex = uv.x;
+   highp float angley = uv.y;
+   highp float sx = sin(anglex);
+   highp float cx = cos(anglex);
+   highp vec3 dir = vec3(0.0, 0.0, 0.0);
+   dir.x = sin(angley) * cx;
+   dir.y = cos(angley);
+   dir.z = sin(angley) * sx;
+   frag = texture(tex, dir);
+}