Move physics mod into "other" modpack (#382)

mods/other/physics/init.lua

@@ -0,0 +1,47 @@
+physics = {}
+
+local players = {}
+
+minetest.register_on_joinplayer(function(player)
+	players[player:get_player_name()] = {}
+end)
+
+minetest.register_on_leaveplayer(function(player)
+	players[player:get_player_name()] = nil
+end)
+
+local function update(name)
+	assert(players[name])
+	local player = minetest.get_player_by_name(name)
+	local override = {
+		speed   = 1,
+		jump    = 1,
+		gravity = 1
+	}
+
+	for _, layer in pairs(players[name]) do
+		for attr, val in pairs(layer) do
+			override[attr] = override[attr] * val
+		end
+	end
+
+	player:set_physics_override(override)
+end
+
+function physics.set(pname, name, modifiers)
+	assert(players[pname] and not players[pname][name])
+	players[pname][name] = modifiers
+	update(pname)
+end
+
+function physics.change(pname, name, modifier)
+	assert(players[pname] and players[pname][name])
+	players[pname][name] = modifier
+	update(pname)
+end
+
+function physics.remove(pname, name)
+	assert(players[pname] and players[pname][name])
+	players[pname][name] = nil
+	update(pname)
+end