Added basic test mode for debug builds

shaders/test/1.frag

@@ -0,0 +1,33 @@
+/* Request transforms and basic uniforms to assert nothing here breaks */
+
+#include ":util/smooth.glsl"
+
+in vec4 gl_FragCoord;
+
+#request uniform "screen" screen
+uniform ivec2 screen;
+
+#request uniform "audio_sz" audio_sz
+uniform int audio_sz;
+
+#request uniform "audio_l" audio_l
+#request transform audio_l "window"
+#request transform audio_l "fft"
+#request transform audio_l "gravity"
+#request transform audio_l "avg"
+uniform sampler1D audio_l;
+
+#request uniform "audio_r" audio_r
+#request transform audio_r "window"
+#request transform audio_r "fft"
+#request transform audio_r "gravity"
+#request transform audio_r "avg"
+uniform sampler1D audio_r;
+
+out vec4 fragment;
+
+void main() {
+    float dummy_result0 = smooth_audio(audio_l, audio_sz, gl_FragCoord.x / float(screen.x));
+    float dummy_result1 = smooth_audio(audio_r, audio_sz, gl_FragCoord.x / float(screen.x));
+    fragment = vec4(1.0, 0, 0, float(1) / float(3));
+}

shaders/test/2.frag

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+/* Pass the initial results to a dummy shader to assert that linking works correctly */
+
+in vec4 gl_FragCoord;
+
+#request uniform "prev" tex
+uniform sampler2D tex;    /* screen texture    */
+
+out vec4 fragment; /* output */
+
+void main() {
+    fragment = texelFetch(tex, ivec2(gl_FragCoord.x, gl_FragCoord.y), 0);
+}

shaders/test/3.frag

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+/* Assert that the premultiply step works */
+#include ":util/premultiply.frag"