Spell Duration Formula 11

[noudess]

I noticed that a few lower level spells using duration formula 11 don't yield the results the GUI expects. For example, minor shielding ends up lasting the full duration of 27 minutes on the server while the GUI sets it to 30 * (level + 3).

Talking in the IRC, demonstar looked something up and said that formula 11 should be exactly that, which makes sense to me.

However, duration formula 11 on the server just returns duration - explaining why it comes back max value.

I changes the server code to for spell duration 11 to:

return std::min((level+3) * 30,duration)

and I like the results.

However, this formual is used by a ton of spells. Do you guys want this fix, or is the server code there for other issues? I didn't want to put out a pull request without getting further input.