Move the project to the src layout to ensure we are testing on the
generated package rather than the checked out source tree.

isoparse: Fail with inconsistent time separators

Call .decode() only for binary data

As the function is wrapped around a decorator that converts the input to
bytes, when an exception is raised that includes the value, it contains
the value as bytes (b"<val>"). To provide the expected str in Python 3,
decode that to unicode.

This will result in `u""` for Python 2 callers, but given that we plan
to drop support for Python 2 in the short term, it feels acceptable.

Save an unnecessary len call.

We can handle both bytes and bytearray in the same way in Python 2 and
Python 3.

Co-authored-by: Mario Corchero <mariocj89@gmail.com>

Fail when separators are used inconsistently to split the time porting
of a string. Even if more restrictive, we have warned that we were going
to fail on invalid cases of ISO formatted strings. This will prevent
invalid iso formatted strings from being unexpectedly parsed.

Periodic update of all links that point to redirects or http targets
when an https target is available.