make: add Ubuntu Zesty docker targets (.deb and ppa) Zesty Zapus was released on 2017-04-13 and will be supported until 2018-01.

docker: install less as a build-time dependency in deb-based distros It's needed since 387a76cac28e, otherwise dpkg-checkbuilddeps errors out.

py3: add utility to forward __str__() to __bytes__() It calls unifromlocal() instead of sysstr() because __bytes__() may contain locale-dependent values such as paths.

share: use dict literal instead of dict(key=value) check-code.py has the rule, but it isn't smart enough to catch this.

py3: use r'' to prevent conversion to bytes by transformer

py3: define __bytes__ for basefilectx class The implementation is shamely copied from the __str__ function

py3: check for bytes instead of str in isinstance

py3: convert kwargs' keys' to str using pycompat.strkwargs() On Python 3, we must have keys of keyword arguments as str.

py3: convert kwargs keys' back to bytes using pycompat.byteskwargs()

py3: use "%d" % val for int rather than pycompat.bytestr Earlier I used pycompat.bytestr() to convert integers to bytes, but we can do b"%d" % val to convert that int to bytes. b'' is already added by the transformer. Thanks to Yuya for suggesting this.