[systemd] Clear up units

Plasma core is moved away from being a template. This makes it easier
for others to mark themselves as being after. A new readme is added to
explain the design.

gmenu-dbusmenu-proxy/plasma-gmenudbusmenuproxy.service.in

 [Unit]
 Description=Proxies GTK DBus menus to a Plasma readable format
 PartOf=graphical-session.target
+After=plasma-core.target
 
 [Service]
 ExecStart=@CMAKE_INSTALL_FULL_BINDIR@/gmenudbusmenuproxy

ksmserver/plasma-restoresession.service.in

 [Unit]
 Description=KDE Session Management Server
-After=plasma-ksmserver.service plasma-xembedsniproxy.service plasma-gmenudbusmenuproxy.service
+After=graphical-session.target
+RefuseManualStart=yes
 
 [Service]
 Type=oneshot
 ExecStart=-@QtBinariesDir@/qdbus org.kde.ksmserver /KSMServer org.kde.KSMServerInterface.restoreSession
 Slice=session.slice
-RefuseManualStart=yes

startkde/systemd/CMakeLists.txt

 ecm_install_configured_files(INPUT plasma-ksplash-ready.service.in @ONLY
                                                    DESTINATION ${SYSTEMD_USER_UNIT_INSTALL_DIR})
 
-install(FILES plasma-core@.target DESTINATION ${SYSTEMD_USER_UNIT_INSTALL_DIR})
+install(FILES plasma-core.target DESTINATION ${SYSTEMD_USER_UNIT_INSTALL_DIR})
 install(FILES plasma-workspace@.target DESTINATION ${SYSTEMD_USER_UNIT_INSTALL_DIR})
 
 add_executable(kde-systemd-start-condition kde-systemd-start-condition.cpp)

startkde/systemd/README.md

+# Startup
+
+Startup can be summarised as being:
+
+plasma-core.target
+plasma-workspace@.target
+graphical-session.target
+
+plasma-workspace@ is the target explicitly activated.
+
+## X11 and wayland
+
+plasma-workspace@ is a template file that ends with x11 or wayland. That will then require the correct kwin_
+startup order can be different between the two.
+
+## Wants & Order
+Note that in systemd dependencies (wants/wantedby) counter-intuitively do not determine order.
+
+plasma-workspace wants graphical-session, meaning it will make it something started by it, but it also explicitly comes before graphical-session.
+
+The order of events is:
+plasma-core does anything that adjusts environment variables
+plasma-workspace@ starts all runtime services
+graphical-session is at a point where everything including runtime services are up
+
+## Adding a new service
+
+If it should only be used on plasma it should be wanted by plasma-core or plasma-workspace@.
+
+That service is responsible for setting "After=plasma-core.target" if we need envs set up.

startkde/systemd/plasma-core@.target → startkde/systemd/plasma-core.target

 [Unit]
 Description=KDE Plasma Workspace Core
-Wants=plasma-plasmashell.service plasma-kwin_%i.service plasma-kcminit.service plasma-kded.service plasma-kcminit-phase1.service graphical-session-pre.target
+Wants=plasma-plasmashell.service plasma-kcminit.service plasma-kded.service plasma-kcminit-phase1.service graphical-session-pre.target
 Requires=plasma-ksmserver.service
 BindsTo=plasma-ksmserver.service
 After=graphical-session-pre.target
+RefuseManualStart=yes

startkde/systemd/plasma-workspace@.target

 [Unit]
 Description=KDE Plasma Workspace
-Requires=plasma-core@%i.target plasma-ksplash-ready.service
+Requires=plasma-kwin_%i.service plasma-core.target xdg-desktop-autostart.target graphical-session.target
+Wants=plasma-restoresession.service plasma-xembedsniproxy.service plasma-gmenudbusmenuproxy.service plasma-powerdevil.service plasma-ksplash-ready.service
 BindsTo=graphical-session.target
-Wants=xdg-desktop-autostart.target plasma-xembedsniproxy.service plasma-gmenudbusmenuproxy.service plasma-restoresession.service
-After=plasma-core.target
+Before=graphical-session.target xdg-desktop-autostart.target plasma-ksplash-ready.service plasma-restoresession.service

xembed-sni-proxy/plasma-xembedsniproxy.service.in

 [Unit]
 Description=Handle legacy xembed system tray icons
 PartOf=graphical-session.target
+After=plasma-core.target
 
 [Service]
 ExecStart=@CMAKE_INSTALL_FULL_BINDIR@/xembedsniproxy