Add dark mode symbols to Sierra assets

Keep existing files for the Any (light) appearance. For Dark appearance,
add pictures with similar sizes, copied from Apple's SFSymbols.app 

Vienna needs dark mode support for the tab overflow symbol.

Author: barijaona

MMTabBarView/MMTabBarView/Sierra.xcassets/Color.colorset/Contents.json

@@ -0,0 +1,38 @@
+{
+  "colors" : [
+    {
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "1.000",
+          "green" : "1.000",
+          "red" : "1.000"
+        }
+      },
+      "idiom" : "universal"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "1.000",
+          "green" : "1.000",
+          "red" : "1.000"
+        }
+      },
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

MMTabBarView/MMTabBarView/Sierra.xcassets/MMSierraOverflow.imageset/Contents.json

@@ -1,21 +1,52 @@
 {
   "images" : [
     {
-      "idiom" : "universal",
       "filename" : "MMSierraOverflow.pdf",
+      "idiom" : "universal",
       "scale" : "1x"
     },
     {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "filename" : "MMSierraOverflowDark.pdf",
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
       "idiom" : "universal",
       "scale" : "2x"
     },
     {
       "idiom" : "universal",
       "scale" : "3x"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "idiom" : "universal",
+      "scale" : "3x"
     }
   ],
   "info" : {
-    "version" : 1,
-    "author" : "xcode"
+    "author" : "xcode",
+    "version" : 1
   }
-}
+}

MMTabBarView/MMTabBarView/Sierra.xcassets/MMSierraOverflow.imageset/MMSierraOverflowDark.pdf

@@ -1,21 +1,52 @@
 {
   "images" : [
     {
-      "idiom" : "universal",
       "filename" : "MMSierraTabClose.pdf",
+      "idiom" : "universal",
       "scale" : "1x"
     },
     {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "filename" : "MMSierraTabCloseDark.pdf",
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
       "idiom" : "universal",
       "scale" : "2x"
     },
     {
       "idiom" : "universal",
       "scale" : "3x"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "idiom" : "universal",
+      "scale" : "3x"
     }
   ],
   "info" : {
-    "version" : 1,
-    "author" : "xcode"
+    "author" : "xcode",
+    "version" : 1
   }
-}
+}

MMTabBarView/MMTabBarView/Sierra.xcassets/MMSierraTabClose.imageset/Contents.json

@@ -1,22 +1,53 @@
 {
   "images" : [
     {
-      "idiom" : "universal",
       "filename" : "MMSierraTabEdited.png",
+      "idiom" : "universal",
       "scale" : "1x"
     },
     {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "filename" : "MMSierraTabEditedDark.pdf",
       "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
       "filename" : "MMSierraTabEdited@2x.png",
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "idiom" : "universal",
       "scale" : "2x"
     },
     {
       "idiom" : "universal",
       "scale" : "3x"
+    },
+    {
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "idiom" : "universal",
+      "scale" : "3x"
     }
   ],
   "info" : {
-    "version" : 1,
-    "author" : "xcode"
+    "author" : "xcode",
+    "version" : 1
   }
-}
+}