Request: Auto-break lines at specific line length

When writing HTML documents, I want my lines to break at 100 characters automatically. The only other editor for Linux I've known to support this is Quanta Plus, but it's no longer maintained starting at Ubuntu 12. :(

Please add the ability to specify auto-break points for lines.

Ideally:

  ~ While typing, carriage returns are added automatically at the specified line length.

  ~ When a single string (w/o whitespace) exceeds the line limit, it *will not* break the string.

  ~ When editing an existing line and making it longer, the overflow text will be prefixed to the next line and all following lines cascade, thus always maintaining proper line lengths and filling them as much as possible (instead of simply adding a new line in the middle for a few words the overflowed).

Thanks!