remove unused strings

src/_locales/en/messages.json

@@ -318,34 +318,6 @@
         "message": "Site",
         "description": "Scope will be full hostname of site"
     },
-    "settingsMatrixAutoReloadPrompt" : {
-        "message": "When the matrix is closed, smart reload these tabs:",
-        "description": ""
-    },
-    "settingsMatrixAutoReloadNone" : {
-        "message": "None",
-        "description": ""
-    },
-    "settingsMatrixAutoReloadCurrent" : {
-        "message": "Current",
-        "description": ""
-    },
-    "settingsMatrixAutoReloadAll" : {
-        "message": "All",
-        "description": ""
-    },
-    "settingsMatrixAutoReloadInfo" : {
-        "message": "Whenever you make changes in the matrix which can affect the display and/or behavior of one or more pages, <i>uMatrix</i> will reload affected pages automatically when you close the matrix.",
-        "description": ""
-    },
-    "settingsSubframeColor" : {
-        "message": "Blocked frames:&ensp;Color",
-        "description": "English: Blocked frames:&ensp;Color"
-    },
-    "settingsSubframeOpacity" : {
-        "message": "Opacity",
-        "description": "English: Opacity"
-    },
     "settingsCollapseBlocked" : {
         "message": "Collapse placeholder of blocked elements",
         "description": "English: Collapse placeholder of blocked elements"