Added C64 theme

Author: demyanovs

README.md

@@ -45,6 +45,7 @@ echo $highlighter->parse();
 * obsidian
 * far
 * vs2015
+* c64
 
 ### Customization
 ```php

src/Themes/Theme.php

@@ -183,4 +183,30 @@ private function vs2015Theme() : void
         self::setPHPKeywordColor('#569CD6; font-weight: bold;');
         self::setPHPStringColor('#D69D85;');
     }
+
+    private function c64Theme() : void
+    {
+        // Default
+        self::setDefaultColor('#70A4B2;');
+        self::setBackgroundColor('#352879');
+        self::setCommentColor('#6C5EB5;');
+        self::setKeywordColor('#FFFFFF;');
+        self::setVariableColor('#70A4B2');
+        self::setStringColor('#B8C76F;');
+        self::setHtmlColor('#70A4B2;');
+        self::setFlagColor('#588D43;');
+
+        // XML
+        self::setXMLTagColor('#70A4B2; font-weight;');
+        self::setXMLAttrNameColor('#9A6759;');
+        self::setXMLAttrValueColor('#9AD284;');
+        self::setXMLInfoColor('#6C6C6C;');
+
+        // PHP
+        self::setPHPDefaultColor('#FFFFFF;');
+        self::setPHPCommentColor('#9AD284;');
+        self::setPHPHtmlColor('#70A4B2;');
+        self::setPHPKeywordColor('#70A4B2; font-weight: bold;');
+        self::setPHPStringColor('#B8C76F;');
+    }
 }

src/Traits/SetOptions.php

@@ -5,29 +5,29 @@
 trait SetOptions
 {
 
-    private static $_defaultColor;
+    private static $_defaultColor = '';
 
-    private static $_backgroundColor;
+    private static $_backgroundColor = '';
 
-    private static $_commentColor;
+    private static $_commentColor = '';
 
-    private static $_keywordColor;
+    private static $_keywordColor = '';
 
-    private static $_variableColor;
+    private static $_variableColor = '';
 
-    private static $_stringColor;
+    private static $_stringColor = '';
 
-    private static $_htmlColor;
+    private static $_htmlColor = '';
 
-    private static $_flagColor;
+    private static $_flagColor = '';
 
-    private static $_XMLTagColor;
+    private static $_XMLTagColor = '';
 
-    private static $_XMLAttrNameColor;
+    private static $_XMLAttrNameColor = '';
 
-    private static $_XMLAttrValueColor;
+    private static $_XMLAttrValueColor = '';
 
-    private static $_XMLInfoColor;
+    private static $_XMLInfoColor = '';
 
     /**
      * @param string $color