Refactor and rewrite.

Perl script is removed in favour of C. Stale documentation and initfiles
are removed for now also.

C interface works, but still needs work (for example, mDNS is missing) -
see TODO.

audio_dummy.c

@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include "audio.h"
+
+int Fs;
+long long starttime, samples_played;
+
+static int dummy_init(int argc, char **argv) {
+    return 0;
+}
+
+static void dummy_deinit(void) {
+}
+
+static void dummy_start(int sample_rate) {
+    Fs = sample_rate;
+    starttime = 0;
+    samples_played = 0;
+    printf("dummy audio output started at Fs=%d Hz\n", sample_rate);
+}
+
+static void dummy_play(short buf[], int samples) {
+    struct timeval tv;
+
+    // this is all a bit expensive but it's long-term stable.
+    gettimeofday(&tv, NULL);
+
+    long long nowtime = tv.tv_usec + 1e6*tv.tv_sec; 
+
+    if (!starttime)
+        starttime = nowtime;
+    
+    samples_played += samples;
+
+    long long finishtime = starttime + samples_played * 1e6 / Fs;
+
+    usleep(finishtime - nowtime);
+}
+
+static void dummy_stop(void) {
+    printf("dummy audio stopped\n");
+}
+
+audio_ops audio_dummy = {
+    .init = &dummy_init,
+    .deinit = &dummy_deinit,
+    .start = &dummy_start,
+    .stop = &dummy_stop,
+    .play = &dummy_play,
+    .volume = NULL
+};