We do not accept open filedescriptors as argument for `WordList`
anymore. This seems to be the only way to make sure we can open/close
wordlist files whenever we want.

The `argparse.FileType` type is considered bad style. Cf.
http://bugs.python.org/issue13824. With this FileType we cannot tell
when to close a file after reading (which should be done for most
regular wordlists) or not (in case of input from stdin).

`WordList` accepts both, already opened files and also file paths. As
this class can better care for closing open files after use, we should
not open files if not neccessary.

Files already opened by third-parties should be closed by them.

Since Python3.2 SafeConfigParser is an alias for ConfigParser and
emits warnings when imported. We want to avoid these warnings.

Logging was available all the time but not yet activated. We now
enable logging when the main script is executed. This makes the
`verbose` commandline option functional.

When using `realdice` randomness source and picking values out of short
sequences (sequences shorter than the number of dice sides), we might
require additional dice throws (if a value rolled is not in range of
sequence length). We now print a hint when this happens.

We avoid the modulo operation now, if it comes to small sequences.
Instead we discard invalud rolls and require new ones.

Sequences with lenths != s**n (with s:= number of dice sides, n := any
natural number) require an extra roll.

The number of rolls is cruical for the whole `choice` distribution and
a specialized function is much better testable.

The EFF list is currently certainly the scientifically most advanced
list. Thanks to @anarcat for proposing this switch! The securedrop
list is still available.

RealDiceRandomSource and its tests updated to expect argparse.Namespace objects instead of dicts (fix for using the 'realdice' randomness source)

Make the tests succeed. In wordlists we now also accept

  '1-2-3-4 someterm'

for numbered entries. We still support '1234 somterm'.

The Electronic Frontier Foundation published own wordlists, which
were, as it looks, carefully assembled. See

https://www.eff.org/deeplinks/2016/07/new-wordlists-random-passphrases

for details.

We ship now with the long list.

As we can only increase verbosity with commandline flags, we
should set the least verbose log level by default.

Tell at least, what level can be set.

When we set logging levels, then handlers must support this.

While it is nice to have a working plugin example, it looks also a bit
overcomplicated to me. It is better for contributors, if they can find
things (like CLI argument parsing) in one (foreseeable) place and do
not have for things scattered over the whole project.

For plugin documentation we can use the sphinx docs. Or maybe provide
a sample plugin in tests.

This argument makes sense together with ``realdice`` randomsource
and tells how many sides the dice we use have. Six by default.

The RealDiceRandomSource will support own commandline arguments. This
is handled by an own classmethod called `update_argparser` that is
called upon initialization of diceware.

If plugins want to work with their own commandline args, we allow
this by calling their `update_argparser` methods. This has to be a
classmethod, if it exists.