Integrate band selection into the files app.

This consists of:
1) Moving both BandSelect* classes into MultiSelectManager as nested
classes. This removes extra layers of indirection and makes code easier
to comprehend.
2) Fixing an issue where band selection could start within an item
instead of only within margins between items.
3) Adding "provisional selection" support to the Selection class. This
gives band select the ability to select some items "temporarily" such
that when the band select no longer covers those items, they are
deselected.
4) Adding glue code between the classes.

Bug: 23081429, 23083146, 20669231

Change-Id: I0dc57e2c0d2ccedb3e1218f0e496de637be227a2
diff --git a/src/com/android/documentsui/DirectoryFragment.java b/src/com/android/documentsui/DirectoryFragment.java
index 240cdda..c28806b 100644
--- a/src/com/android/documentsui/DirectoryFragment.java
+++ b/src/com/android/documentsui/DirectoryFragment.java
@@ -1773,8 +1773,6 @@
         }
 
         @Override
-        public void afterActivityCreated(DirectoryFragment fragment) {
-            new BandSelectManager(fragment.mRecView, fragment.mSelectionManager);
-        }
+        public void afterActivityCreated(DirectoryFragment fragment) {}
     }
 }