Specify high precision for water shader varyings on GLES to fix shaky reflection/refraction texture sampling. Closes #1593.

bin/CoreData/Shaders/GLSL/Water.glsl

@@ -4,11 +4,18 @@
 #include "ScreenPos.glsl"
 #include "Fog.glsl"
 
+#ifndef GL_ES
 varying vec4 vScreenPos;
 varying vec2 vReflectUV;
 varying vec2 vWaterUV;
-varying vec3 vNormal;
 varying vec4 vEyeVec;
+#else
+varying highp vec4 vScreenPos;
+varying highp vec2 vReflectUV;
+varying highp vec2 vWaterUV;
+varying highp vec4 vEyeVec;
+#endif
+varying vec3 vNormal;
 
 #ifdef COMPILEVS
 uniform vec2 cNoiseSpeed;