* 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
- remove unnecessary initialization of string to ""
- use empty() instead of checking size()
- use emplace_back instead of push_back
- use nullptr instead of NULL
- remove unnecessary call to .data() on string
- use character overload of find_first_of() instead of passing a string