lastfm: Use source nick if none is supplied to !lastfm.
lastfm: Use source nick if none is supplied to !lastfm.

Former-commit-id: a4d50573945b13e111e26d8fc534881cd79d7591 [formerly a50ff7be5aea8d61fea38626676ac6691805eda5]
Former-commit-id: 725ebb1657d935ff25fdd826a45571c99408c6f7
haste/ivar2,torhve/ivar2,torhve/ivar2,torhve/ivar2