This commit also introduces a new shared-bindings directory which is used to store the common Python -> C binding code. By having a shared directory we can ensure that the Python API across ports is the same. Each port will have a corresponding common-hal directory which provides definitions for the C api used in the shared-bindings code. That way the compiler can enforce the C api.
To migrate to this new shared API create a common-hal directory within your port and change the Makefile to compile both the shared-bindings and common-hal files. See atmel-samd/Makefile SRC_BINDINGS for an example.
