Increase line limit for summary text

Doing this to accomodate some really long warning text in a
checkbox widget. Needs 5 lines for English. Probably a lot
more for German, etc., so increasing it to 10 lines.

Please don't abuse that. 4 lines is still a reasonable max.

Change-Id: Ife5858f2165cb2bc046ce606f29d31010d26ecc2