MaxScale should refuse to load modules if unexpected configuration options are found.

This request was originally made in http://bugs.mariadb.com/show_bug.cgi?id=154 in August 2013, but I ran into it again while testing filters.

If you add an option to MaxScale.cnf that doesn't exist for a module, the module writes an error to the error log, but continues loading. For example:

2015-03-21 06:24:57   Error : Unexpected parameter 'filter' for object 'RW Split Router' of type 'service'.

The correct option is "filters", not "filter". But in this case, the router loads anyway, without the filters defined. This may mean that a user is allowed to execute queries that should be blocked. In other cases, it could have other harmful effects.

I think that the module should refuse to load if there are unexpected/unused configuration options. That is the behavior of MySQL server and it can be very dangerous to have queries going places you don't expect, or have queries allowed to execute in the first place, because you've mis-spelled a configuration variable or option or think you're setting some option that doesn't exist.