Time to update GSoC/EVoC ideas page

[Rob Clark]

Just a friendly reminder that now would be a good time to update the
wiki page for GSoC/EVoC ideas:

  https://www.x.org/wiki/SummerOfCodeIdeas/

There are currently still some stale ideas there (and probably plenty
of missing good ideas).

Also, I've added a "Potential Mentors" section.  Please add yourself
if you are willing to be a mentor (and what sorts of projects you
would be willing to mentor)

BR,
-R