New MV Hydro Machine (#412)

* New MV hydro with upgraded power

The LV hydro is easy to make giving lot of power. The New hydro MV will put a tier system to it; thereby giving more incentive to player to pursue MV hydro plus a little survival aspect. This is a result of [Detailed discussion which is here](https://github.com/minetest-mods/technic/issues/411). Thanks to VanessaE for a good talk and support and enthusiasm to make one :) This will now produce around 175 EU (in between 150-200, so basically average). The MV hydro will give 10x more power than this one. :)

technic/machines/LV/water_mill.lua

@@ -1,6 +1,6 @@
 -- A water mill produces LV EUs by exploiting flowing water across it
--- It is a LV EU supplyer and fairly low yield (max 120EUs)
--- It is a little under half as good as the thermal generator.
+-- It is a LV EU supplyer and fairly low yield (max 180EUs)
+-- It is a little over half as good as the thermal generator.
 
 local S = technic.getter
 
@@ -29,11 +29,9 @@ end
 local run = function(pos, node)
 	local meta             = minetest.get_meta(pos)
 	local water_flow       = 0
-	local lava_nodes       = 0
 	local production_level = 0
 	local eu_supply        = 0
-	local max_output       = 35 * 45 -- four param2's at 15 makes 60, cap it lower for "overload protection"
-									 -- (plus we want the gen to report 100% if three sides have full flow)
+	local max_output       = 4 * 45 -- keeping it around 180, little more than previous 150 :)
 
 	local positions = {
 		{x=pos.x+1, y=pos.y, z=pos.z},
@@ -49,7 +47,7 @@ local run = function(pos, node)
 		end
 	end
 
-	eu_supply = math.min(35 * water_flow, max_output)
+	eu_supply = math.min(4 * water_flow, max_output)
 	production_level = math.floor(100 * eu_supply / max_output)
 
 	meta:set_int("LV_EU_supply", eu_supply)