Remove bootstrap and old-style staticfiles template tags to make it executable

aleksis/apps/chronos/templates/chronos/edit_substitution.html

 {# -*- engine:django -*- #}
 
 {% extends "core/base.html" %}
-{% load bootstrap4 i18n %}
-
-{% block bootstrap4_extra_head %}
-  {{ block.super }}
-  {{ edit_substitution_form.media.css }}
-{% endblock %}
-
-{% block bootstrap4_extra_script %}
-  {{ block.super }}
-  {{ edit_substitution_form.media.js }}
-{% endblock %}
-
-
-{% block bootstrap4_title %}{% blocktrans %}Edit substitution{% endblocktrans %} - {{ block.super }}{% endblock %}
+{% load i18n %}
 
 {% block page_title %}{% blocktrans %}Edit substitution{% endblocktrans %}{% endblock %}
 

aleksis/apps/chronos/templates/chronos/lessons_day.html

 {# -*- engine:django -*- #}
 
 {% extends "core/turnable.html" %}
-{% load bootstrap4 i18n %}
+{% load  i18n %}
 {% load render_table from django_tables2 %}
 
-{% block bootstrap4_title %}{% blocktrans %}Lessons{% endblocktrans %} - {{ block.super }}{% endblock %}
 
 {% block current_content %}
   {% render_table lessons_table %}

aleksis/apps/chronos/templates/chronos/substitutions.html

 {# -*- engine:django -*- #}
 
 {% extends "core/turnable.html" %}
-{% load bootstrap4 i18n %}
+{% load  i18n %}
 {% load render_table from django_tables2 %}
 
-{% block bootstrap4_title %}{% blocktrans %}Substitutions{% endblocktrans %} - {{ block.super }}{% endblock %}
 
 {% block current_content %}
   {% render_table substitutions_table %}

aleksis/apps/chronos/templates/chronos/tt_week.html

 {# -*- engine:django -*- #}
 
 {% extends "core/turnable.html" %}
-{% load bootstrap4 data_helpers i18n staticfiles %}
+{% load data_helpers i18n static %}
 
-{% block bootstrap4_extra_head %}
-  {{ block.super }}
-  <link rel="stylesheet" href="{% static 'css/chronos/timetable.css' %}" />
-  {{ select_form.media.css }}
-{% endblock %}
-
-{% block bootstrap4_extra_script %}
-  {{ block.super }}
-  {{ select_form.media.js }}
-{% endblock %}
-
-{% block bootstrap4_title %}{% blocktrans %}Timetable{% endblocktrans %} - {{ block.super }}{% endblock %}
 
 {% block current_content %}
   <form method="get">