Better base_shutdown.lua

 * Add built-in support for trigger-based buttons (blue_security_trigger/red_security_trigger)
 * Add built-in support for Lua-defined security shutdown length (SECURITY_LENGTH)
 * Add built-in support for turning on/off lights, brushes, trigger_ff_clips, and trigger_hurts
 * Add some helpful team-oriented trigger definitions in base_teamplay.lua
There's nothing that's nearly as concise. The alternative would be:
```lua
local opposite_team
if team == "red" then
  opposite_team = "blue"
else
  opposite_team = "red"
end
```
See: http://lua-users.org/wiki/TernaryOperator

It just goes with the language.