add Support for GenreRadio
add support for list_genres API method
add SongType to CopyConstructor of Song
some artist api queries don't require an artist, reflect that nicer in source
use string comparison again, adding a boolean could compromise binary compatibility
fix incorrect boolean operator when checking for api calls that can be made without an artist set
change documentation of parse functions a little bit to make their functionality more clear
Merge pull request #2 from Horrendus/master

add Genre Support