Merge from trunk.

 - Add `quick_erase` for unordered. `erase_return_void` is now deprecated.
   Fixes #3966
 - Avoid collision between 0 and 0.5. Fixes #4038


[SVN r60980]

libs/functional

@@ -1 +1 @@
-Subproject commit ce5cb3f9df29058cbe845a685297ecad3285fa84
+Subproject commit 5ed2ed3b6bbd506ea9878abf235158e8be196f3d

libs/unordered

@@ -1 +1 @@
-Subproject commit 958738c7af5a1102ad4b3621840066ba9d9c86b6
+Subproject commit fe2a6c521bfd9a3b1aff8c360e75cf71161ed7bd