'Safe Start', prevents weapons from being fired and sets playable units as invincible while active.

If this gets merged, an explanation on the wiki will be needed.  Translations for the stringtable are still needed as well.  I'm still not too high on the name, but I can't think of anything better at the moment.

-ADDED
f/common/f_safeStart.sqf, controls logic of 'safe start'
f/server/f_safeStartLoop.sqf, tracks time and broadcasts variable to clients, server-side only
f/common/f_safeStartHint.sqf, loops while 'safe start' is active, displays time remaining, client-side only
f/common/f_safety.sqf, toggles safety on and off via 'fired' event handler and allowdamage, client-side only

-CHANGED
description.ext, added 'safe start' parameter
init.sqf, added 'safe start' call
stringtable.xml, added 'safe start' parameter reference

![gqjfo7oh](https://f.cloud.github.com/assets/1514890/1145501/7f7bbd8e-1e1a-11e3-82ad-f0e3efb6dff0.jpg)
![bpihtmj](https://f.cloud.github.com/assets/1514890/1145502/80cdfdaa-1e1a-11e3-9c4b-d04161c62b67.png)