Bunch of generic code standard items. Will need a cleanup.

src/FactorGraphs/FactorGraph.php

@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace DNW\Skills\FactorGraphs;
 
 class FactorGraph

src/FactorGraphs/KeyedVariable.php

@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace DNW\Skills\FactorGraphs;
 
 class KeyedVariable extends Variable

src/FactorGraphs/Message.php

@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace DNW\Skills\FactorGraphs;
 
 use DNW\Skills\Numerics\GaussianDistribution;

src/FactorGraphs/Schedule.php

@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace DNW\Skills\FactorGraphs;
 
 abstract class Schedule implements \Stringable