This extension also gives you access to an object API that is currently not documented anywhere. It uses the Svn, SvnWc, SvnWcSchedule and SvnNode classes. So you can't redeclare those names.
Here are some basics on how to use it:
<?php
$svn = new Svn;
$log = $svn->log('https://svn.example/trunk/', Svn::HEAD);
?>
Basically you can use all functions documented here by replacing the svn_ prefix with $svn-> object. Same for constants, most can be used directly from the objects.
If you're interested, make sure to check the extension source code to find out more.