Merge branch 'master' into 'master'

Clean up colors definitions

Use system constants when possible; move the red color definition from `styles.xml` to `colors.xml` and tune it to match the [Material Design guidelines](http://www.google.com/design/spec/patterns/errors.html#errors-user-input-errors).

See merge request !121

F-Droid/res/drawable/swap_button_normal.xml

@@ -2,7 +2,7 @@
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
     <item>
         <shape>
-            <solid android:color="@color/white" />
+            <solid android:color="@android:color/white" />
             <padding
                 android:top="1dp"/>
         </shape>
@@ -17,4 +17,4 @@
                 android:bottom="10dp" />
         </shape>
     </item>
-</layer-list>
+</layer-list>

F-Droid/res/drawable/swap_button_pressed.xml

@@ -2,7 +2,7 @@
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
     <item>
         <shape>
-            <solid android:color="@color/white" />
+            <solid android:color="@android:color/white" />
             <padding
                 android:top="1dp"/>
         </shape>
@@ -17,4 +17,4 @@
                 android:bottom="10dp" />
         </shape>
     </item>
-</layer-list>
+</layer-list>

F-Droid/res/layout/install_app_details.xml

@@ -32,7 +32,7 @@ installation screens
         android:layout_width="32dip"
         android:layout_height="32dip"
         android:layout_marginStart="8dip"
-        android:background="@color/transparent"
+        android:background="@android:color/transparent"
         android:layout_alignParentStart="true"
         android:gravity="start"
         android:scaleType="centerCrop"/>

F-Droid/res/values/colors.xml

@@ -3,6 +3,7 @@
     <color name="signed">#ffcccccc</color>
     <color name="unsigned">#ffCC0000</color>
     <color name="unverified">#ff999999</color>
+    <color name="red">#ffdd2c00</color>
 
     <color name="fdroid_blue">#ff1976d2</color>
     <color name="fdroid_blue_dark">#ff0d47a1</color>
@@ -20,7 +21,6 @@
     <color name="swap_wifi_likely_to_work">#00a14b</color>
 
     <color name="shadow">#cc222222</color>
-    <color name="transparent">#00000000</color>
 
     <color name="perms_costs_money">#fff4511e</color>
 

F-Droid/res/values/styles.xml

@@ -20,10 +20,6 @@
         <item name="alertDialogTheme">@style/AlertDialogThemeLight</item>
     </style>
 
-    <color name="black">#FF000000</color>
-    <color name="white">#FFFFFFFF</color>
-    <color name="red">#FFFF0000</color>
-
     <style name="AppThemeDark" parent="AppBaseThemeDark">
         <!-- customizations that are not API-level specific go here. -->
     </style>
@@ -49,7 +45,7 @@
     </style>
 
     <style name="SwapTheme.StartSwap" parent="AppThemeLight">
-        <item name="android:background">@color/white</item>
+        <item name="android:background">@android:color/white</item>
     </style>
 
     <style name="SwapTheme.AppList" parent="AppThemeLight">