Locales: use http-accept-language or cookie (#976)

* Locales: use http-accept-language or "language"-cookie

* Add user-setting "locale"

Rename CULTURE to DEFAULT_LOCALE

* Use LocaleMiddleware also in dev mode

* CORS: don't require authentication on OPTIONS

* Use a standard user-settings-control and start a new generic user settings page, not a separate page for the locale setting

* Fixed (broken by myself) link-return handling

* Clarify language settings

* Removed unneeded files

* Better user settings icon

* Added localization hints

Co-authored-by: Bernd Bestel <bernd@berrnd.de>

views/usersettings.blade.php

@@ -0,0 +1,30 @@
+@extends('layout.default')
+
+@section('title', $__t('User settings'))
+@section('activeNav', '')
+@section('viewJsName', 'usersettings')
+
+@section('content')
+<div class="row">
+	<div class="col">
+		<h2 class="title">@yield('title')</h2>
+		<hr>
+	</div>
+</div>
+<div class="row">
+	<div class="col-lg-6 col-xs-12">
+
+		<div class="form-group">
+			<label for="locale">{{ $__t('Language') }}</label>
+			<select class="form-control user-setting-control" id="locale" data-setting-key="locale">
+				<option value="">{{ $__t('Default') }}</option>
+				@foreach($languages as $lang)
+					<option value="{{ $lang }}" @if(GROCY_LOCALE == $lang) checked @endif>{{ $__t($lang) }}</option>
+				@endforeach
+			</select>
+		</div>
+
+		<a href="{{ $U('/') }}" class="btn btn-success link-return">{{ $__t('OK') }}</a>
+	</div>
+</div>
+@stop