Fixed Connection Throttling

Hi,

it would be great to have a throttling feature in Maxscale, to avoid using too many connections in the backend, and to avoid sending connection errors to applications (up to some level)

Scenario:
MariadB> set global max_connections = 100;
maxadmin> set max_active_connections = 100;
maxadmin> set max_waiting_connections = 200;

When 100 connections are opened, the following will be waiting for a free slot, not returning max_connection error to client.

Thanks in advance!
Joffrey