[CSM] Client side modding

* rename GameScripting to ServerScripting
* Make getBuiltinLuaPath static serverside
* Add on_shutdown callback
* Add on_receiving_chat_message & on_sending_chat_message callbacks
* ScriptApiBase: use IGameDef instead of Server
  This permits to share common attribute between client & server
* Enable mod security in client side modding without conditions

builtin/client/register.lua

@@ -0,0 +1,62 @@
+
+core.callback_origins = {}
+
+function core.run_callbacks(callbacks, mode, ...)
+	assert(type(callbacks) == "table")
+	local cb_len = #callbacks
+	if cb_len == 0 then
+		if mode == 2 or mode == 3 then
+			return true
+		elseif mode == 4 or mode == 5 then
+			return false
+		end
+	end
+	local ret
+	for i = 1, cb_len do
+		local cb_ret = callbacks[i](...)
+
+		if mode == 0 and i == 1 or mode == 1 and i == cb_len then
+			ret = cb_ret
+		elseif mode == 2 then
+			if not cb_ret or i == 1 then
+				ret = cb_ret
+			end
+		elseif mode == 3 then
+			if cb_ret then
+				return cb_ret
+			end
+			ret = cb_ret
+		elseif mode == 4 then
+			if (cb_ret and not ret) or i == 1 then
+				ret = cb_ret
+			end
+		elseif mode == 5 and cb_ret then
+			return cb_ret
+		end
+	end
+	return ret
+end
+
+--
+-- Callback registration
+--
+
+local function make_registration()
+	local t = {}
+	local registerfunc = function(func)
+		t[#t + 1] = func
+		core.callback_origins[func] = {
+			mod = core.get_current_modname() or "??",
+			name = debug.getinfo(1, "n").name or "??"
+		}
+		--local origin = core.callback_origins[func]
+		--print(origin.name .. ": " .. origin.mod .. " registering cbk " .. tostring(func))
+	end
+	return t, registerfunc
+end
+
+core.registered_on_shutdown, core.register_on_shutdown = make_registration()
+core.registered_on_receiving_chat_messages, core.register_on_receiving_chat_messages = make_registration()
+core.registered_on_sending_chat_messages, core.register_on_sending_chat_messages = make_registration()
+
+