wimmel.frag: Define the required precisionHEADmaster

Or we get errors like:
fragment shader info: 0:1(1): error: no precision specified this scope
for type `vec2'
0:4(1): error: no precision specified this scope for type `vec2'
0:6(1): error: no precision specified this scope for type `vec4'
0:13(2): error: no precision specified this scope for type `float'
0:17(2): error: no precision specified this scope for type `vec4'
0:18(2): error: no precision specified this scope for type `vec4'

1 files changed, 2 insertions, 0 deletions

diff --git a/wimmel.frag b/wimmel.frag
index 58d633e..48a9692 100644
--- a/wimmel.frag
+++ b/wimmel.frag
@@ -1,3 +1,5 @@
+precision mediump float;
+
 varying vec2 v_texcoord;
 uniform sampler2D tex;
 uniform sampler2D tex2;