Make scroll wheel work with SDL
Bring back old style SDL scroll events represented as mouse buttons; Support newer 'wheel' event to support Chrome; Support vertical as well as horizontal deltas.
Code conventions and sign fix according to pull request feedback
Bump version
fix file argument changing before callback in async_wget; fixes #2349
warn on bad exports, fixes #2338
Merge branch 'sdl_mouse_wheel' of github.com:jechter/emscripten into incoming

Conflicts:
	emscripten-version.txt
commented closure in benchmarks
testcases for issue #2350
Merge branch 'incoming' of https://github.com/mhenschel/emscripten
Revert "fix progress events for non mozilla browsers"

This reverts commit 04d60d0d89cd06b1924e1257b28049cf43733388.