Update libxmp, reorganize project structure, add Makefile

Makefile

@@ -0,0 +1,17 @@
+EMHOME = /usr/lib/emscripten
+
+.PHONY: libxmp
+
+libxmp: 
+	mkdir -p build
+	${EMHOME}/emcmake cmake -B build libxmp
+	${EMHOME}/emmake make -C build
+	${EMHOME}/emcc -O3 build/libxmp.a -o build/libxmp.js -s WASM=1 -s EXPORTED_FUNCTIONS=@libxmp.exported -s EXPORT_ALL=1 -s BINARYEN_METHOD="native-wasm" -s EXPORTED_RUNTIME_METHODS='["cwrap","UTF8ToString","HEAPU8","HEAPF32","HEAP16"]' -s ALLOW_MEMORY_GROWTH=1 -s MODULARIZE=1 -s JSPI=1 -s EXPORT_NAME='libxmp' -s ENVIRONMENT='web,worker' -s SINGLE_FILE=0
+
+build: libxmp
+
+package:
+	mkdir -p out
+	zip -D -j out/WAXMPlayer.xpi src/* build/libxmp.js build/libxmp.wasm
+
+all: build package