Avoid using `long` if it does not exist.
Try making mktemp always return bytes.
Enforce byte strings, not native strings.
The maximum of Py_ssize_t is the more relevant value here.  Plus there is no maxint on Python 3.
bytes for filenames elsewhere, too.
Don't use the deprecated assertEquals
Drop ancient Python 2.3 support which used deprecated unittest apis.
Lots of Python 3.2 porting work
UTF-9 is sort of a thing but not a thing we're concerned with here.
Merge pull request #6 from pyca/python3-fixes

Python 3 fixes.