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

docs/docs/changelog/v0.5.0.md

@@ -17,6 +17,8 @@
 - Fixes #281 - Slow Handling of Large Sets of Recipes
 
 ## Features and Improvements
+- 'Dinner this week' shows a warning when no meal is planned yet
+- 'Dinner today' shows a warning when no meal is planned yet
 
 ### General
 - New Toolbox Page!
@@ -37,4 +39,7 @@
 
 ### Behind the Scenes
 - Unified Sidebar Components
-- Refactor UI components to fit Vue best practices (WIP)
+- Refactor UI components to fit Vue best practices (WIP)
+- The API returns more consistent status codes
+- The API returns error code instead of error text when appropriate 
+  - ⚠️ May cause side-effects if you were directly consuming the API