rename some variables and begin compiled sim c code

sim/group.lua

@@ -5,7 +5,7 @@ function Group.new()
 	local o = {
 		state = false,
 		fxstate = false,
-		updatetick = 0,
+		update_tick = 0,
 		wires = {},
 		out_ports = {},
 		in_ports = {},
@@ -179,7 +179,7 @@ function Group.setstate(group, state)
 		local sim = GSim
 		
 		group.state = state
-		group.updatetick = sim.currenttick
+		group.update_tick = sim.current_tick
 		
 		for k, gate in ipairs(group.gates_update) do
 			Simulation.queuegate(sim, gate)