martin modes, and some bugfixes to get them working

martin.h

@@ -0,0 +1,23 @@
+#ifndef MARTIN_H
+#define MARTIN_H
+
+#include "wav.h"
+#include <stdint.h>
+
+typedef struct {
+  uint8_t vis_code;
+  int width;
+  int height;
+  double sync_ms;
+  double sync_porch_ms;
+  double separator_ms;
+  double scan_ms;
+} martin_mode_t;
+
+extern const martin_mode_t MARTIN_M1;
+extern const martin_mode_t MARTIN_M2;
+
+void martin_encode_image(wav_t *wav, uint8_t *rgb, const martin_mode_t *mode);
+int sstv_encode_martin(const char *input_image, const char *output_wav, const martin_mode_t *mode);
+
+#endif // !MARTIN_H