Major code-base update and clean-up.

XML integration moving along nicely. Successfully parsing of config
files with pugixml without major or minor errors. Chose to write own xml
file writing function for default configuration creation. Code cleaned
up very nicely, fuller documentation and updated doxygen pages.

Moving forward, Songbird's configuration and language files for English
and German will be written and Songbird's general configuration and
language file formats should be designed and coded.

Next milestone before release: Fully implemented GUI dialog box for
changing display language.