remove unused resources

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

app/src/main/res/values/strings.xml

@@ -416,9 +416,6 @@ How to translate with transifex:
     <string name="nc_user">User</string>
     <string name="nc_guest">Guest</string>
     <string name="nc_following_link">User following a public link</string>
-    
-    <string name="nc_filter_unread" translatable="false">nc_filter_unread</string>
-    <string name="nc_filter_mention" translatable="false">nc_filter_mention</string>
 
     <!-- Browser component -->
     <string name="nc_file_browser_back">Back</string>
@@ -709,6 +706,5 @@ How to translate with transifex:
     <string name="custom">Custom</string>
     <string name="set">Set</string>
     <string name="calendar">Calendar</string>
-    <string name="empty" translatable="false"/>
 
 </resources>