Move Exceptions in a separate directory + Fixed Range function

Signed-off-by: davidarendsen <davidarendsen@hey.com>

src/Expression/Base.php

@@ -2,6 +2,8 @@
 
 namespace Arendsen\FluxQueryBuilder\Expression;
 
+use Arendsen\FluxQueryBuilder\Exception\ExpressionNotImplementedException;
+
 abstract class Base {
 
 	/**

src/Expression/ExpressionNotImplementedException.php

@@ -1,7 +0,0 @@
-<?php
-
-namespace Arendsen\FluxQueryBuilder\Expression;
-
-use Exception;
-
-class ExpressionNotImplementedException extends Exception {}