Move Encoding class away from the Language namespace

Language\Encoding::__mbMimeEncode -> Convert\MimeEncode::__mbMimeEncode
Langauge\Encoding::checkConvertEncoding -> Check\Encoding::checkConvertEncoding
Langauge\Encoding::setErrorChar -> Check\Encoding::setErrorChar
Langauge\Encoding::getErrorChar -> Encoding::getErrorChar
Langauge\Encoding::convertEncoding -> Convert\Encoding::convertEncoding

Also fixed encoding check that not only a code point but a string can
also be used as a parameter.

Update phpunit tests and split them out for each class

Normal test page is still combined for all classes but updated to
correctly use each class

4dev/tests/CoreLibsConvertMimeEncodeTest.php

@@ -0,0 +1,101 @@
+<?php
+
+declare(strict_types=1);
+
+namespace tests;
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Test class for Convert\MimeEncode
+ * @coversDefaultClass \CoreLibs\Convert\MimeEncode
+ * @testdox \CoreLibs\Convert\MimeEncode method tests
+ */
+final class CoreLibsConvertMimeEncodeTest extends TestCase
+{
+	/**
+	 * Undocumented function
+	 *
+	 * @return array
+	 */
+	public function mbMimeEncodeProvider(): array
+	{
+		return [
+			// 0: input string
+			// 1: encoding
+			// 2: expected
+			'standard UTF-8' => [
+				'Test string',
+				'UTF-8',
+				'Test string'
+			],
+			'long text UTF-8' => [
+				'The quick brown fox jumps over the lazy sheep that sleeps in the ravine '
+					. 'and has no idea what is going on here',
+				'UTF-8',
+				'The quick brown fox jumps over the lazy sheep that sleeps in the ravine '
+					. 'and has no idea what is going on here'
+			],
+			'standard with special chars UTF-8' => [
+				'This is ümläßtと漢字もカタカナ！!^$%&',
+				'UTF-8',
+				'This is =?UTF-8?B?w7xtbMOkw59044Go5ryi5a2X44KC44Kr44K/44Kr44OK77yBIV4k?='
+					. "\r\n"
+					. ' =?UTF-8?B?JQ==?=&'
+			],
+			'35 chars and space at the end UTF-8' => [
+				'12345678901234567890123456789012345 '
+					. 'is there a space?',
+				'UTF-8',
+				'12345678901234567890123456789012345 '
+					. 'is there a =?UTF-8?B?c3BhY2U/?='
+			],
+			'36 chars and space at the end UTF-8' => [
+				'123456789012345678901234567890123456 '
+					. 'is there a space?',
+				'UTF-8',
+				'123456789012345678901234567890123456 '
+					. 'is there a =?UTF-8?B?c3BhY2U/?='
+			],
+			'36 kanji and space UTF-8' => [
+				'カタカナカタカナかなカタカナカタカナかなカタカナカタカナかなカタカナカタ '
+					. 'is there a space?',
+				'UTF-8',
+				"=?UTF-8?B?44Kr44K/44Kr44OK44Kr44K/44Kr44OK44GL44Gq44Kr44K/44Kr44OK44Kr?=\r\n"
+					. " =?UTF-8?B?44K/44Kr44OK?=\r\n"
+					. " =?UTF-8?B?44GL44Gq44Kr44K/44Kr44OK44Kr44K/44Kr44OK44GL44Gq44Kr44K/44Kr?=\r\n"
+					. " =?UTF-8?B?44OK44Kr44K/?= is there a =?UTF-8?B?c3BhY2U/?="
+			]
+		];
+	}
+
+	/**
+	 * mb mime header encoding test
+	 *
+	 * @covers ::__mbMimeEncode
+	 * @dataProvider mbMimeEncodeProvider
+	 * @testdox mb encoding target $encoding [$_dataName]
+	 *
+	 * @return void
+	 */
+	public function testUuMbMimeEncode(string $input, string $encoding, string $expected): void
+	{
+		// encode string first
+		$encoded = \CoreLibs\Convert\MimeEncode::__mbMimeEncode($input, $encoding);
+		// print "MIME: -" . $encoded . "-\n";
+		$this->assertEquals(
+			$expected,
+			$encoded
+		);
+		$decoded = mb_decode_mimeheader($encoded);
+		// print "INPUT  : " . $input . "\n";
+		// print "DECODED: " . $decoded . "\n";
+		// back compare decoded
+		$this->assertEquals(
+			$input,
+			$decoded
+		);
+	}
+}
+
+// __END__