Added extension string methods to export and import text.

* Configuration.cs: Added furigana marks (XML exporting/importing)

* StringExtensions.cs: Added extension methods to export / import text
  (XMLs)

* Format.cs: Now sets the Format File to be always updated.

* Program.cs: Added test to check Subtitles from Ninokuni
  (exporting/importing process).

* Rom.cs: Fixed bug.