I haven't been able to find a way to encode a bytes object in
hexadecimal, where in Python 2.x I'd go "str.encode('hex')".

I recommend adding a bytes.tohex() method (in the same vein as the
existing bytes.fromhex class method).

I've attached a patch which adds this method to the bytes and bytearray
classes (in the C code). Also included documentation and test cases.

Style note: The bytesobject.c and bytearrayobject.c files are all over
the place in terms of tabs/spaces. I used tabs in bytesobject and spaces
in bytearrayobject, since those seemed to be the predominant styles in
either file.

Commit log:

Added "tohex" method to bytes and bytearray objects. Also added
documentation and test cases.