* examples : refactor common code into a library
* examples : refactor common SDL code into a library
* make : update Makefile to use common libs
* common : fix MSVC M_PI ..
* addon.node : link common lib
Same as the command-line tool "command", but runs in the browser
Also, added helper script "extra/deploy-wasm.sh" and fixed some timing
constants for the WASM examples.