The same mechanism that is used for modules can be used for the
configuration of the core objects. This removes the need for the redundant
code that validates various values that is already present in the code
that modules use.
Relaced router_options with configuration parameters in the createInstance
router entry point. The same needs to be done for the filter API as barely
any filters use the feature.
Some routers (binlogrouter) still support router_options but using it is
deprecated. This had to be done as their use wasn't deprecated in 2.2.
If a router parameter has no default value, the previous value would be
returned as an empty string. A debug assertion would be triggered when a
parameter of this type was altered.
When a new router parameter is encountered and the alteration fails, the
modified value in the service need to be removed. Previously, the new
value would have been stored in the service with an empty value which
would have caused problems.
Pre-loading users for all threads at startup significantly reduces the
chance for failures caused by the lazy initialization of the user database
done by the authenticators.
If users are not loaded at startup and the connection limit for all
servers is reached, authentication in MaxScale will fail not due to too
many connections but due to the lack of authentication data. This causes
repeated reloading of users, which floods the log with messages, and
unnecessary stress on the cluster itself.
The internal header directory conflicted with in-source builds causing a
build failure. This is fixed by renaming the internal header directory to
something other than maxscale.
The renaming pointed out a few problems in a couple of source files that
appeared to include internal headers when the headers were in fact public
headers.
Fixed maxctrl in-source builds by making the copying of the sources
optional.
