Remove language selection from the general configuration

refs #6073
Update preference form so that it suits the new language negotiation

refs #6073
Update web bootstrapping to suit the new localization procedure

Icinga\Application\Web::setupInternationalization now sets up the locale
from the current session first, if any, and falls back to the one from the
user's preferences, if any.

refs #6073
Merge branch 'master' into feature/localization-form-6073

Conflicts:
	application/forms/Config/GeneralForm.php
	application/forms/Preference/GeneralForm.php
	library/Icinga/Application/Web.php
Add new `section` column to icingaweb_user_preference table
Add new table columns and change the preferences DB save process
Add translation to preference tab title
Remove timezone element from the ApplicationConfigForm
Add timezone detection to `setupTimezone' in ApplicationBootstrap
Fix `setupTimezone' and `setupInternationalization' for user preferences
Fix IniStore to save and load proper user preferences
Change PreferenceForm and add the ability to store preferences in the current session
Add user account menu and move logout and preferences inside it
Fix empty preferences array warning in the DbStore
Update User\Store\DbStoreTest
Update User\Store\IniStoreTest
Merge branch 'master' into feature/localization-form-6073

Conflicts:
	library/Icinga/Application/ApplicationBootstrap.php
	test/php/library/Icinga/User/Store/DbStoreTest.php
Fix timezone setup

The CLI must not try to use our web timezone detection thingy.

refs #6073
Fix locale setup

The CLI must not try to use HTTP_ACCEPT_LANGUAGE. Avoided double try-catch blocks.

refs #6073
Merge branch 'master' into feature/localization-form-6073