Reduce binary size to ~1MB

- Recompiled main.cpp with -s WASM=1
- Recompiled FFTW with O3 flag

README.md

@@ -71,5 +71,5 @@ To build this project you need Emscripten compiler. Additionally, you need [FFTW
   - Ultrasonic sound transmission does not work on most devices. Probably hardware limitations?
   - In presence of multiple local networks, cannot currently select which one to use. Always the first one is used
   - There is occasionally sound cracking during transmission. Need to optimize the Tx code
-  - The size of the emscripten generated .js is too big (~4MB). Rewrite in pure JS?
+  - The size of the emscripten generated .js is too big (~1MB). Rewrite in pure JS?
   - On mobile, using Firefox, the page can remain running in the background even after closing the tab

compile.sh

@@ -2,7 +2,7 @@
 
 echo "static const char * BUILD_TIMESTAMP=\"`date`\";" > build_timestamp.h
 
-em++ -Wall -Wextra -O3 -std=c++11 -s USE_SDL=2 ./main.cpp -o wave.js -I ./fftw-3.3.3/api ./lib/libfftw3f.a \
+em++ -Wall -Wextra -O3 -std=c++11 -s USE_SDL=2 -s WASM=1 ./main.cpp -o wave.js -I ./fftw-3.3.3/api ./lib/libfftw3f.a \
     -s EXPORTED_FUNCTIONS='["_getText", "_getSampleRate", "_setText", "_getAverageRxTime_ms", "_setParameters",
                             "_getFramesLeftToRecord", "_getFramesToRecord",
                             "_getFramesLeftToAnalyze", "_getFramesToAnalyze",