Reading wikipedia

This commit contains basic tools to load Wikipedia graph to Cassovary:

1. RedirectsExtractor - tool to parse Wikipedia dumps and get all redirects to a single file.
2. DumpToGraphConverter - tool to parse Wikipedia dumps and print links graph as adjacency list for Cassovary
3. HashMapsBasedWikipediaGraph - classes that read Wikipedia graph and redirects from previous tools and store them in a graph and hash table.

Using this code it's possible to load Wikipedia to Cassovary. Steps take following times (on server class machine):
1. Redirects - 2000s
2. Dumps to Graph - 1800s
3. Reading - 304 s.
All redirects pages point to the same main one. This is done in the first line of the pages text and looks like:
```
<page>
    <title>AsWeMayThink</title>
    <id>30</id>
    (...)
    <text xml:space="preserve">#REDIRECT [[As_We_May_Think]] {{R from CamelCase}}       
    </text>
    (...)
</page>
```