added ellipsis truncation to overflows to TOC entries

For indented entries in the TOC, if the chapter name is longer than the width of the TOC box, the name will wrap to the second line and be unaligned. Instead of wrapping, just truncate the chapter name using text-overflow: ellipsis.
Merge pull request #225 from ricefield/master

added ellipsis truncation to overflows to TOC entries