Added shaders

Shaders/GodotRetro/Screen Shaders/LensDistortion.gdshader

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+//SHADER ORIGINALY CREADED BY "jcant0n" FROM SHADERTOY
+//MODIFIED AND PORTED TO GODOT BY AHOPNESS (@ahopness)
+//LICENSE : CC0
+//COMATIBLE WITH : GLES2, GLES3, WEBGL
+//SHADERTOY LINK : https://www.shadertoy.com/view/4sSSzz
+
+shader_type canvas_item;
+
+uniform sampler2D SCREEN_TEXTURE : hint_screen_texture, filter_linear_mipmap;
+
+uniform float strength :hint_range(-0.035, 0.035) = 0.0;
+
+void fragment(){
+	vec2 Resolution = 1.0 / SCREEN_PIXEL_SIZE; 
+	vec2 uv = FRAGCOORD.xy / Resolution.xy;
+	float aspectRatio = Resolution.x / Resolution.y;
+	
+	
+	vec2 intensity = vec2(strength * aspectRatio);
+	
+	vec2 coords = uv;
+	coords = (coords - 0.5) * 2.0;
+	
+	vec2 realCoordOffs;
+	realCoordOffs.x = (1.0 - coords.y * coords.y) * intensity.y * (coords.x); 
+	realCoordOffs.y = (1.0 - coords.x * coords.x) * intensity.x * (coords.y);
+	
+	vec4 color = texture(SCREEN_TEXTURE, uv - realCoordOffs);	 
+	
+	COLOR = vec4(color);
+}