education: mark task-edu-* as metapackages

metapackages are expanded into a list of its dependencies.
This achieves two goals:
- the installer shows which packages will be installed
  together with the metapackage
- after deleting meta package, apt-get autoremove not
  will remove its immediate dependencies

pkg.in/lists/education/base

@@ -1,4 +1,4 @@
-task-edu
+task-edu@META
 
 # WINE
 glibc-gconv-modules@i586

pkg.in/lists/education/gradeschool

@@ -1 +1 @@
-task-edu-gradeschool
+task-edu-gradeschool@META

pkg.in/lists/education/highschool

@@ -1 +1 @@
-task-edu-highschool
+task-edu-highschool@META

pkg.in/lists/education/kde5

@@ -1 +1 @@
-task-edu-kde5@!E2K
+task-edu-kde5@META

pkg.in/lists/education/misc

@@ -315,7 +315,7 @@ systemd-settings-enable-showstatus
 systemd-settings-enable-log-to-tty12
 
 # Other architecture-depended utilities
-task-edu-tools
+task-edu-tools@META
 
 # Russian Root CA certificate
 ca-certificates-digital.gov.ru

pkg.in/lists/education/preschool

@@ -1 +1 @@
-task-edu-preschool
+task-edu-preschool@META

pkg.in/lists/education/secondary_vocational

@@ -1 +1 @@
-task-edu-secondary-vocational
+task-edu-secondary-vocational@META

pkg.in/lists/education/server-apps-edu

@@ -1,5 +1,5 @@
 deploy
-task-edu-server-apps
+task-edu-server-apps@META
 installer-feature-repo-add
 installer-feature-resolver-bind-stage3
 installer-feature-apache2-indexhtml-stage3

pkg.in/lists/education/teacher

@@ -1 +1 @@
-task-edu-teacher
+task-edu-teacher@META

pkg.in/lists/education/university

@@ -1 +1 @@
-task-edu-university
+task-edu-university@META

pkg.in/lists/education/video-conferencing

@@ -1 +1 @@
-task-edu-video-conferencing@!E2K
+task-edu-video-conferencing@META