There was no way to see if report-{host,port,user,password} were set up.

Fixed with introducing new global variables.
The variables are made read-only because of a possible need to change them
most probably require the slave server restart.

Todo: transform the startup options to be CHANGE master parameters - i.e
to deprecate `report-' options, and to change the new vars 
to be updatable at time of CHANGE master executes with new
values.