SafeZones are not properly stored

[Joshua732]

The safezones are stored without their map name which causes them to show up on other maps.

[Joshua732]

changing the getMapFilename() function code to

local mapname = string.gsub(game.GetMap(), "[^%a%d-_]", "_")
return mapSZDir .. mapname .. ".txt"

seems to fix it as the spaces in the .gsub seem to cause the problem