getLyLines()
extract new preprocessLyFile() function
extract runLilyPond() method
remove extra space in docstring
fix help string for --debug option
README.md: remove use of 1st person
README.md: mention that English translation of thesis has been started
runLilyPond: move chdir() next to safeRun() invocation
runLilyPond(): allow arbitrary options to lilypond
runLilyPond(): return output
getNumStaffLines(): use runLilyPond()
fix \include of user's own .ly files (issue #29)

https://github.com/aspiers/ly2video/issues/29