EXT-8473 FIXED Fixed renaming inventory items without hitting Enter.

Problem:

The bug was caused by the fix of EXT-6682 that prematurely forgets the item
being renamed (by resetting mRenameItem) whenever the renamer input field loses focus.
That's why we couldn't actually finish renaming item.

Fix:

The code is quite messy, but I'll try to explain.

There are three cases when we should hide the renamer:
1) ESC key is hit (just hide).
2) ENTER key is hit (rename, then hide).
3) renamer loses focus (rename, then hide).

In the first two cases we manually remove the renamer from the popups
list -- by calling gViewerWindow->removePopup(mRenamer).
In the third case that's done automatically.
So, in all cases the onRenamerLost() pop-up is called that hides the renamer
and only *then* resets mRenameItem.
Not only this approach fixes the bug -- I hope it's a bit more straightforward too.

Reviewed by Seraph at https://codereview.productengine.com/secondlife/r/854/

--HG--
branch : product-engine