(emms-lyrics-set-timer): Don't repeat lyrics already displayed when
resumed.

When resuming from a paused session, played lyrics timers will have a
negative time, but timer-duration is so nice to convert it as
positive, thus messing lyrics display.  Check the `time' to fix.

Thanks to Ian D.
* lisp/emms-score.el: Stop `emms-score-load-hash' from reading empty score file.

Reads the score file into a string, then only proceeds if the string
is not empty.  I ran it myself, and appears to be working correctly.

Thanks to Ian D.
* doc/emms.texinfo: Close @defun statement.