The 'events' and 'script' config values were defined for every monitor.
Removed the extra definitions and moved the variables to MXS_MONITOR.
MariaDBMonitor was printing config values a second time, they are
already printed by the caller.
Moved the events enum definition to the internal header since it's no longer
required by modules.
Added a default config setting "all" to 'events' to clarify that it enables
all events.
The common monitor parameters are now stored as module-style
parameters. This makes the error reporting as well as the type checks for
the parameters consistent with parameters declared by the modules.
MonitorDestroy() (renamed to monitor_destroy()) will be used for
actually destroying the monitor instance, that is, execute
destroyInstance() on the loaded module instance and freeing the
the monitor instance.
TODO: monitor_deactivate() could do all the stuff which is currently
done to the monitor in config_runtime(), instead of just
turning off the flag.
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.
