Proposal for support of multiple languages

[CristianCantoro]

This pull request is the beginning of the work for addressing issue #2.

The idea is to create some submodules that deal each one with a given language (see for example in the pull request the subdirectories en and it in wikiciteparser) where the language-depended functions and/or data should be added.

In particular in this pull request the __init__.py files for the submodules en and it both contain the definition of the citation template names that are supported within the set citation_template_names. The content of __init__.py is executed when the module is imported.

The submodules should contain all the code that is language specific, then you can use dynamic import like this:

    lang_module = __import__(lang)
    if template_name in lang_module.citation_template_names:
        return template_name

where lang is a string with a specific language code (e.g. en, it)

To support new languages one just need to create another subdirectory (e.g. es, de, etc.) and implement a list of needed function. For now, you just need to define the set citation_template_names

Do you think that this design could work for this library? Do you have any comments?

I should add also some test for itwiki templates.

[wetneb]

Excellent, thanks, happily merging!