Fix #29 - Reset the FileManager when MainScreen is closed

This fixes the issue where the FileManager wouldn't be reset, when the
user switched back to the SelectionScreen.

src/FileManager.lua

@@ -129,6 +129,13 @@ function FileManager.remove(fileName)
     createSortedList(extensions);
 end
 
+function FileManager.reset()
+    extensions = {};
+    sortedList = {};
+    totalFiles = 0;
+    colors = nil;
+end
+
 -- ------------------------------------------------
 -- Getters
 -- ------------------------------------------------

src/screens/MainScreen.lua

@@ -160,6 +160,10 @@ function MainScreen.new()
         camera:move(dt);
     end
 
+    function self:close()
+        FileManager.reset();
+    end
+
     function self:quit()
         if ConfigReader.getConfig('options').removeTmpFiles then
             ConfigReader.removeTmpFiles();