Added many shader source files

This should include the latest version of every shader that was in the
2007 SDK. It also includes a smattering of debug shaders, both VR
distortion shaders, and other assorted shaders that will hopefully be
useful.

None of these new files are included in the game shader DLL project. If
you need to modify one of these shaders for use in your mod you will
need to rename it so that you don't collide with the version of that
shader that lives in stdshader_dx9.dll.

mp/src/materialsystem/stdshaders/VertexLitGeneric_Detail_additive_selfillum.psh

@@ -0,0 +1,15 @@
+; DYNAMIC: "WRITEONETODESTALPHA" "0..1"
+ps.1.1
+
+; Get the color from the texture
+tex t0
+tex t3
+
+mul r0, c3, t0
+mul r0.rgb, v0, r0		; Apply lighting
+mul_x2 r0.rgb, c0, r0   ; * 2 * (overbrightFactor/2)
+mad r0.rgb, c1, t3, r0
+
+#if WRITEONETODESTALPHA
++mov r0.a, c4			; make alpha 255
+#endif