More localization (#358)

* Translate missing items on About page

* Localize import summary dialog

* Make site menu translation reactive

* Localize import options

* Include semi colon in string

* Move API texts to frontend + better status codes

* Provide feedback to user when no meal is planned

* Fix API tests after latest rework

* Add warning for API changes in changelog

* Refactor API texts handling

* Refactor API texts handling #2

* Better API feedback

* Rearrange strings hierarchy

* Add messages upon recipe updated

* Fix 'recipe effected' typo

* Remove snackbar usage in backend

* Translate toolbox

* Provide feedback for tags CRUD

* Fix messed up merge

* Translate sign-up form

* Better feedback for sign-up CRUD

* Refactor log-in API texts handling

* No error message when user is not authenticated

* Remove unimportant console log

frontend/src/pages/Admin/ManageUsers/index.vue

@@ -16,12 +16,12 @@
         </v-tab>
 
         <v-tab>
-          {{ $t("user.sign-up-links") }}
+          {{ $t("signup.sign-up-links") }}
           <v-icon>mdi-account-plus-outline</v-icon>
         </v-tab>
 
         <v-tab>
-          {{ $t("user.groups") }}
+          {{ $t("group.groups") }}
           <v-icon>mdi-account-group</v-icon>
         </v-tab>
       </v-tabs>