MemberProfile: admins can't demote other admins

TODO.md

@@ -1,5 +1,6 @@
 # TODO
 
+- idlemanager: what if setPresence call fails due to network?
 - block power level change when offline
 - fix power level control button layout when apply button is loading
 

src/gui/Pages/Chat/RoomPane/MemberView/MemberProfile.qml

@@ -166,7 +166,7 @@ HListView {
                 root.canSetPowerLevels &&
                 (
                     root.ownPowerLevel > member.power_level ||
-                    root.ownPowerLevel === 100
+                    (root.ownPowerLevel === 100 && member.id === userId)
                 )
 
             label.text: qsTr("Power level:")