Move shaders into glsl and hlsl directories

Move `data/shaders` to `data/shaders/glsl`
Move `data/hlsl` to `data/shaders/hlsl`

Fix up shader paths in the cpp files to point to the new glsl location.

`data/shaders/hlsl/compile.py` still overwrites the glsl .spv files (for
now).

Issue: #723

data/shaders/glsl/deferredshadows/debug.vert

@@ -0,0 +1,21 @@
+#version 450
+
+layout (location = 0) in vec3 inPos;
+layout (location = 1) in vec2 inUV;
+
+layout (binding = 0) uniform UBO 
+{
+	mat4 projection;
+	mat4 modelview;
+} ubo;
+
+layout (location = 0) out vec3 outUV;
+
+void main() 
+{
+	outUV = vec3(inUV.st, gl_InstanceIndex);
+	vec4 tmpPos = vec4(inPos, 1.0);
+	tmpPos.y += gl_InstanceIndex;
+	tmpPos.xy *= vec2(1.0/4.0, 1.0/3.0);
+	gl_Position = ubo.projection * ubo.modelview * tmpPos;
+}