fix: Getting an aggregate fails when the query has derived fields (de…

…fined in the select section) in the order section

Remove the code duplication in the Query aggregate methods

Added the `addTablesToColumnNames` helper query method

Testing with PHP 7.3 in Travis CI

Updated to QueryScribe v0.9

Updated the QueryScribe version

fix: QueryProxy throws Query Scribe InvalidReturnValueException inste…

…ad of MiniDB InvalidReturnValueException

Amended the readme

Added a note about the file importing to the readme

Updated Query Scribe