Derive mode from DSN function

- Add headers in all files
- Minor field name changes

tests/unit/ParametersTest.php

@@ -1,4 +1,10 @@
-<?php declare(strict_types=1);
+<?php
+/**
+ * @author Daniel J. Summers <daniel@bitbadger.solutions>
+ * @license MIT
+ */
+
+declare(strict_types=1);
 
 namespace Test\Unit;
 
@@ -91,11 +97,11 @@ class ParametersTest extends TestCase
     public function testFieldNamesSucceedsForPostgreSQL(): void
     {
         try {
-            Configuration::$mode = Mode::PgSQL;
+            Configuration::overrideMode(Mode::PgSQL);
             $this->assertEquals([':names' => "{one,two,seven}"],
                 Parameters::fieldNames(':names', ['one', 'two', 'seven']), 'Field name parameters not correct');
         } finally {
-            Configuration::$mode = null;
+            Configuration::overrideMode(null);
         }
     }
 
@@ -103,18 +109,18 @@ class ParametersTest extends TestCase
     public function testFieldNamesSucceedsForSQLite(): void
     {
         try {
-            Configuration::$mode = Mode::SQLite;
+            Configuration::overrideMode(Mode::SQLite);
             $this->assertEquals([':it0' => '$.test', ':it1' => '$.unit', ':it2' => '$.wow'],
                 Parameters::fieldNames(':it', ['test', 'unit', 'wow']), 'Field name parameters not correct');
         } finally {
-            Configuration::$mode = null;
+            Configuration::overrideMode(null);
         }
     }
 
     public function testFieldNamesFailsWhenModeNotSet(): void
     {
         $this->expectException(DocumentException::class);
-        Configuration::$mode = null;
+        Configuration::overrideMode(null);
         Parameters::fieldNames('', []);
     }
 }