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

www/lib/CoreLibs/Convert/Encoding.php

@@ -0,0 +1,60 @@
+<?php
+
+/*
+ * check if string is valid in target encoding
+ */
+
+declare(strict_types=1);
+
+namespace CoreLibs\Convert;
+
+class Encoding
+{
+	/**
+	 * detects the source encoding of the string and if doesn't match
+	 * to the given target encoding it convert is
+	 * if source encoding is set and auto check is true (default) a second
+	 * check is done so that the source string encoding actually matches
+	 * will be skipped if source encoding detection is ascii
+	 *
+	 * @param  string $string          string to convert
+	 * @param  string $to_encoding     target encoding
+	 * @param  string $source_encoding optional source encoding, will try to auto detect
+	 * @param  bool   $auto_check      default true, if source encoding is set
+	 *                                 check that the source is actually matching
+	 *                                 to what we sav the source is
+	 * @return string                  encoding converted string
+	 */
+	public static function convertEncoding(
+		string $string,
+		string $to_encoding,
+		string $source_encoding = '',
+		bool $auto_check = true
+	): string {
+		// set if not given
+		if (!$source_encoding) {
+			$source_encoding = mb_detect_encoding($string);
+		} else {
+			$_source_encoding = mb_detect_encoding($string);
+		}
+		if (
+			$auto_check === true &&
+			isset($_source_encoding) &&
+			$_source_encoding == $source_encoding
+		) {
+			// trigger check if we have override source encoding.
+			// if different (_source is all but not ascii) then trigger
+			// skip if matching
+		}
+		if ($source_encoding != $to_encoding) {
+			if ($source_encoding) {
+				$string = mb_convert_encoding($string, $to_encoding, $source_encoding);
+			} else {
+				$string = mb_convert_encoding($string, $to_encoding);
+			}
+		}
+		return $string;
+	}
+}
+
+// __END__

www/lib/CoreLibs/Convert/MimeEncode.php

@@ -0,0 +1,67 @@
+<?php
+
+/*
+ * alternate for header mime encode to void problems with long strings and
+ * spaces/strange encoding problems.
+ * Orignal issues during PHP5/7
+ */
+
+declare(strict_types=1);
+
+namespace CoreLibs\Convert;
+
+class MimeEncode
+{
+	/**
+	 * wrapper function for mb mime convert
+	 * for correct conversion with long strings
+	 *
+	 * @param  string $string     string to encode
+	 * @param  string $encoding   target encoding
+	 * @param  string $line_break default line break is \r\n
+	 * @return string             encoded string
+	 */
+	public static function __mbMimeEncode(
+		string $string,
+		string $encoding,
+		string $line_break = "\r\n"
+	): string {
+		// set internal encoding, so the mimeheader encode works correctly
+		mb_internal_encoding($encoding);
+		// if a subject, make a work around for the broken mb_mimencode
+		$pos = 0;
+		// after 36 single bytes characters,
+		// if then comes MB, it is broken
+		// has to 2 x 36 < 74 so the mb_encode_mimeheader
+		// 74 hardcoded split does not get triggered
+		$split = 36;
+		$_string = '';
+		while ($pos < mb_strlen($string, $encoding)) {
+			$output = mb_strimwidth($string, $pos, $split, "", $encoding);
+			$pos += mb_strlen($output, $encoding);
+			// if the strinlen is 0 here, get out of the loop
+			if (!mb_strlen($output, $encoding)) {
+				$pos += mb_strlen($string, $encoding);
+			}
+			$_string_encoded = mb_encode_mimeheader($output, $encoding);
+			// only make linebreaks if we have mime encoded code inside
+			// the space only belongs in the second line
+			if ($_string && preg_match("/^=\?/", $_string_encoded)) {
+				$_string .= $line_break . " ";
+			} elseif (
+				// hack for plain text with space at the end
+				mb_strlen($output, $encoding) == $split &&
+				mb_substr($output, -1, 1, $encoding) == " "
+			) {
+				// if output ends with space, add one more
+				$_string_encoded .= " ";
+			}
+			$_string .= $_string_encoded;
+		}
+		// strip out any spaces BEFORE a line break
+		$string = str_replace(" " . $line_break, $line_break, $_string);
+		return $string;
+	}
+}
+
+// __END__