How to display table of contents in two columns?

[Wei-Wei Guo]

Dear all,

I'm working on a songbook, which has many songs. Since the song name is very 
short,
it would be better look putting them in two columns. Can I do this?

BTW, how to set vertical space between the title of ToC and the contents? I 
tried

  tocTitleMarkup = \markup \override #'(baseline-skip . 10) {
    \fill-line { "Table of Contents" }
  }

but it doesn't work.


Best wishes,
Wei-Wei