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/sphericalenvmapping/sem.frag

@@ -0,0 +1,19 @@
+#version 450
+
+layout (binding = 1) uniform sampler2DArray matCap;
+
+layout (location = 0) in vec3 inColor;
+layout (location = 1) in vec3 inEyePos;
+layout (location = 2) in vec3 inNormal;
+layout (location = 3) in flat int inTexIndex;
+
+layout (location = 0) out vec4 outFragColor;
+
+void main()
+{
+	vec3 r = reflect( inEyePos, inNormal );
+	vec3 r2 = vec3( r.x, r.y, r.z + 1.0 );
+	float m = 2.0 * length( r2 );
+	vec2 vN = r.xy / m + .5;
+	outFragColor = vec4( texture( matCap, vec3(vN, inTexIndex)).rgb * (clamp(inColor.r * 2, 0.0, 1.0)), 1.0 );
+}