Add counting parts units: Standalone sheets, double pages, written pages

Close #37

src/enums/MDCountPartsUnit.php

@@ -14,6 +14,9 @@ enum MDCountPartsUnit implements MDValueEnumInterface, JsonSerializable, MDMeasu
     case parts;
     case sheets;
     case pages;
+    case double_pages;
+    case standalone_sheets;
+    case written_pages;
 
     /**
      * Returns a value of this type based on a string.
@@ -28,6 +31,9 @@ enum MDCountPartsUnit implements MDValueEnumInterface, JsonSerializable, MDMeasu
             'parts' => self::parts,
             'pages' => self::pages,
             'sheets' => self::sheets,
+            'double_pages' => self::double_pages,
+            'standalone_sheets' => self::standalone_sheets,
+            'written_pages' => self::written_pages,
             default => throw new MDpageParameterNotFromListException("Unknown parts counting unit"),
         };
 
@@ -46,6 +52,9 @@ enum MDCountPartsUnit implements MDValueEnumInterface, JsonSerializable, MDMeasu
             1 => self::parts,
             2 => self::pages,
             3 => self::sheets,
+            4 => self::double_pages,
+            5 => self::standalone_sheets,
+            6 => self::written_pages,
             default => throw new MDpageParameterNotFromListException("Unknown parts counting unit"),
         };
 
@@ -84,6 +93,9 @@ enum MDCountPartsUnit implements MDValueEnumInterface, JsonSerializable, MDMeasu
             self::parts => 1,
             self::pages => 2,
             self::sheets => 3,
+            self::double_pages => 4,
+            self::standalone_sheets => 5,
+            self::written_pages => 6,
             # default => throw new MDpageParameterNotFromListException("Unknown measurement type"),
         };