Py_LIMITED_API ("abi3") suppprt

[sajith]

Since version 1.5.4, zfec ships a rather large number of wheel packages, but it doesn't have to be necessarily that way. Python 3.x has the concept of a stable ABI (aka "abi3"), and bcrypt, for example, has been able to ship fewer wheels with abi3.

Currently cibuildwheel, which zfec uses to build wheels, does not have direct support for building abi3 wheels, but it is being discussed. Once tooling is available, zfec should ship abi3 wheels.