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/Eyes.psh

@@ -0,0 +1,16 @@
+ps.1.1
+
+;------------------------------------------------------------------------------
+; Draw the eyes
+; t0 - texture
+; t1 - iris
+; t2 - glint
+;------------------------------------------------------------------------------
+
+tex t0
+tex t1
+tex t2
+
+lrp	r0, t1.a, t1, t0		; Blend in the iris with the background 
+mad r0.rgb, r0, v0, t2 +	; Modulate by the illumination, add in the glint
+mov r0.a, t0.a