feat(compiler): Add support for targeting WebAssembly.

The working principle is similar as before with x86, but instead of outputting .asm, it outputs .wat. This can be compiled into .wasm by using the wat2wasm assembler.

templates/amd64-386/player.h

@@ -0,0 +1,50 @@
+// auto-generated by Sointu, editing not recommended
+#ifndef SU_RENDER_H
+#define SU_RENDER_H
+
+#define SU_MAX_SAMPLES     {{.MaxSamples}}
+#define SU_BUFFER_LENGTH   (SU_MAX_SAMPLES*2)
+
+#define SU_SAMPLE_RATE     44100
+#define SU_BPM             {{.Song.BPM}}
+#define SU_PATTERN_SIZE    {{.Song.PatternRows}}
+#define SU_MAX_PATTERNS    {{.Song.SequenceLength}}
+#define SU_TOTAL_ROWS      (SU_MAX_PATTERNS*SU_PATTERN_SIZE)
+#define SU_SAMPLES_PER_ROW (SU_SAMPLE_RATE*4*60/(SU_BPM*16))
+
+#include <stdint.h>
+#if UINTPTR_MAX == 0xffffffff
+    #if defined(__clang__) || defined(__GNUC__)
+        #define SU_CALLCONV __attribute__ ((stdcall))
+    #elif defined(_WIN32)
+        #define SU_CALLCONV __stdcall
+    #endif
+#else
+    #define SU_CALLCONV
+#endif
+
+{{- if .Song.Output16Bit}}
+typedef short SUsample;
+#define SU_SAMPLE_RANGE 32767.0
+{{- else}}
+typedef float SUsample;
+#define SU_SAMPLE_RANGE 1.0
+{{- end}}
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void SU_CALLCONV su_render_song(SUsample *buffer);
+{{- if gt (.SampleOffsets | len) 0}}
+void SU_CALLCONV su_load_gmdls();
+#define SU_LOAD_GMDLS
+{{- end}}
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif