SH Safe Zones

This update is optional!

1. Added option to make Safe Zones offer no damage protection. Good if you want "named" zones around your maps but still have players take damage.

Modified files:

1. sz_config.lua
2. entities/sh_safezone.lua
3. safezones/cl_editor.lua
4. safezones/cl_interface.lua
5. safezones/cl_main.lua
6. safezones/sh_main.lua
7. safezones/sv_main.lua