Sandbox Additions & Modifications

This update changes the sandbox panel in the following ways:
Dangerous canisters (including Plasma and N2O) can now only be spawned by admins, the buttons will appear under the sandbox toggles.
Along with this, the canister spawn menu was removed, due to it's ability to have players grief badly.
Normal players can still spawn Oxygen and Air canisters.
Added "Spawn 50 Wood" and "Spawn 50 Reinforced Glass" buttons for user convenience.