Update readme for import.php and add rtfmimport-readme.md
Change DocumentOutliner to always output outline
Change PreElementAnalyzer to always output pre elements stat
Add and improve stats prefix handling
Prevent processed page from being saved if $dest is null
Implement compare.php

Page-by-page comparison between two MODX RTFM sites including: text
diffs, document outlines and pre element counts
Move text-diff.php to old directory

It has been replaced by compare.php
Enable exclusion of Child Pages sections
Enable building of pagetrees to include in comparison
Remove path filter
Update readme for compare.php
Merge branch 'feature/compare' into develop
Update composer dependencies