Added some more SubqueryFlattener tests
Switch SubqueryFlattenerTest to new parameters

so that intellij can run a single resource
ADded some yaml test for count of count
Don't flatten aggregates with more than one from
Prevent Count(*) on the outside

this can be more lenient, if there's no aggregates on the inside,
then it can be flattened
added default values for desired configurable variables to server.properties
prevent flattening when count refers to expression

you can't do COUNT(c1+3)
Updated readme
Slightly less restrictive for COUNT(*) flattening
Encapsulated method
Added a couple comments
Handle delete/update & null resultColumns
handle null resultColumns correctly

if there's no resultColumns, they can't prevent nesting
Extracted method
Added some more tests
update on multiple variables
add exception
add checks for ddl methods
add retrictions on calling routines
prevent null pointer exceptions when no SecurityService in place