[patch] add "underwave" face attribute

[Aurélien Aptel]

Hi all,

I implemented a new face attribute "underwave". It does exactly what
this thread[1] asked for.
It only works on X11 currently. I've basically followed whatever
"overline" was doing across all the source tree so it should be ok. I
don't have a windows/mac machine to port this feature but it should be
easy to do: just port the changes made to xterm.c to other *term.c.

I've attached the diff and a screenshot of the splash screen with the
default and link face changed to use underwaving.
Note that it looks good on both X11 core fonts and Xft fonts.

I would love to see this merged in emacs so -- if everything is
alright -- what's the next step?

PS: if you receive this message twice you can ignore the other one, sorry.

1: http://thread.gmane.org/gmane.emacs.devel/147873/focus=147905

sample.png
Description: PNG image

underwave.diff
Description: Text Data