fix ASSERTIONS output on bad function pointer calls
update other.test_emcc
put emscripten version in emscripten-version.txt, like other repos
add canvas.style.setProperty in headlessCanvas
release 1.13.0
Merge branch 'incoming' of https://github.com/kripken/emscripten into incoming
Implement emscripten_async_wget2_data

This adds the new function emscripten_async_wget2_data to read from
an XMLHTTPRequest directly into memory while supporting advanced features.
I don't like the way we _malloc and then copy into memory from the XHR
response. Is there any way to just add the XHR response to the heap and save
a memcpy?