added backspace shortcut as alias for delete

src/framework/shortcuts/data/shortcuts-Mac.xml

@@ -514,6 +514,7 @@
   <SC>
     <key>delete</key>
     <seq>Del</seq>
+    <seq>Backspace</seq>
     </SC>
   <SC>
     <key>time-delete</key>

src/framework/shortcuts/data/shortcuts.xml

@@ -514,6 +514,7 @@
   <SC>
     <key>delete</key>
     <seq>Del</seq>
+    <seq>Backspace</seq>
     </SC>
   <SC>
     <key>time-delete</key>

src/framework/shortcuts/data/shortcuts_AZERTY.xml

@@ -523,6 +523,7 @@
   <SC>
     <key>delete</key>
     <seq>Del</seq>
+    <seq>Backspace</seq>
     </SC>
   <SC>
     <key>time-delete</key>

src/notation/internal/notationuiactions.cpp

@@ -202,7 +202,7 @@ const UiActionList NotationUiActions::m_actions = {
              QT_TRANSLATE_NOOP("action", "Select all similar elements with more options")
              ),
     UiAction("delete",
-             mu::context::UiCtxNotationOpened,
+             mu::context::UiCtxNotationFocused,
              QT_TRANSLATE_NOOP("action", "Delete"),
              QT_TRANSLATE_NOOP("action", "Delete the selected element(s)"),
              IconCode::Code::DELETE_TANK