Add profile option to disable underlining links.

Add a configuration item that allows disabling of the underlined links
on mouse hover. The option is profile specific and defaults to the previous
behaviour where links are underlined on hover.

Patch by Amand Tihon <amand.tihon@alrj.com>

BUG: 174261
FIXED-IN: 4.7
CCMAIL: amand.tihon@alrj.com