refactor: change meta class structure to include types.

Introduce requiredness of translations via implemented interface.

src/core/base/ThingThatAcceptsPayments.ts

@@ -12,7 +12,8 @@
  * You should have received a copy of the GNU General Public License along with
  * this program. If not, see <https://www.gnu.org/licenses/>.
  */
-import {SCThing} from '../Thing';
+import {SCThing, SCThingMeta} from '../Thing';
+import {SCMetaTranslations} from '../types/i18n';
 
 /**
  * Types of payment that are accepted at a place.
@@ -31,3 +32,33 @@ export interface SCThingThatAcceptsPaymentsWithoutReferences extends SCThing {
    */
   paymentsAccepted?: SCThingThatAcceptsPaymentsAcceptedPayments[];
 }
+
+/**
+ * Meta information about a thing without references that accepts payments
+ */
+export class SCThingThatAcceptsPaymentsWithoutReferencesMeta extends SCThingMeta implements
+             SCMetaTranslations<SCThingThatAcceptsPaymentsWithoutReferences> {
+  /**
+   * Translations of fields
+   */
+  fieldTranslations = {
+    de: {
+      ... SCThingMeta.getInstance().fieldTranslations.de,
+    },
+    en: {
+      ... SCThingMeta.getInstance().fieldTranslations.en,
+    },
+  };
+
+  /**
+   * Translations of values of fields
+   */
+  fieldValueTranslations  = {
+    de: {
+      ... SCThingMeta.getInstance().fieldValueTranslations.de,
+    },
+    en: {
+      ... SCThingMeta.getInstance().fieldValueTranslations.en,
+    },
+  };
+}