Add the Python/dtoa.c file containing the main algorithms;
add corresponding include file and include in Python.h;
include license information for Python/dtoa.c;
add dtoa.c and dtoa.h to Makefile.
The patch adds wrappers for the Linux epoll syscalls and the BSD kqueue syscalls. Thanks to Thomas Herve and the Twisted people for their support and help.
TODO: Finish documentation documentation