* Updated context menu code to enable visible items that aren't explicitly disabled.

EXP-1758 : Fix crash on login on Mac (bad pointer reference). Might need more work if the intent was to always get that pointer.

The whole sentence was split to two parts:
 First pars was in panel.string and the second one in the text box. I combined them both in "allow_label5" text box and also I deleted unnecessary panel.string with the first part of the sentence.

EXP-1758 WIP Progress spinner not shown during merketplace synch if Merchant Outbox floater was previously minimized
rewrote layout_stack resizing logic to be symmetrical

added throttling to fetchInventoryItem queries

made shift-selection work consistently across folder boundaries

* New confirmation dialog lets them know when a folder was automatically created to contain an item dragged/copied to the outbox.

EXP-1802 FIX -- Create labeled drop target region at bottom of merchant outbox floater for easy top level drop access

* Added generic drop zone that highlights green when its functionality will be used.

EXP-1775 : cleanup a bit PeekMessage() usage, avoid eating one event when reaching MAX_MESSAGE_PER_UPDATE.

* Any drag and drop or copy operation to the merchant outbox that contains one
  or more no-copy items now brings up a single modal dialog prompting the user
  to move the no-copy items to the outbox or to leave them all behind.

EXP-1795 PROGRESS -- Update warning dialog for dragging and dropping no-copy items to Merchant Outbox

* The text associated with EXP-1795 has been updated but the "apply to all"
  checkbox has not been implemented yet.
* Updated the "0 folders" text to be an empty string instead.

Tweaked offset and missed a corner case

* Added a link to the "imports" log from the "done with errors" notification when
  sending folders to the marketplace.

* The "Copy to Outbox" option is now disabled when the item is in the loading state.

* Disabled the "openItem" function on outbox items to prevent default behavior
  when the return button is pressed.

EXP-1791 FIX -- Handle case where initialization with SLM fails in the Merchant Outbox floater in the viewer

* Updated marketplace import to properly handle failed cases of authentications
  and invalid cookies.  The import will reset to an uninitialized state and then
  trigger and initialization followed immediately by an import when appropriate.

made assert match actual error condition for list iterators

reviewed by Leslie

EXP-1791 - Handle case where initialization with SLM fails in the Merchant Outbox floater in the viewer

* Added code to clear and re-initialize the SLM cookie when authentication errors are encountered.
* Re-organized logic for outbox import a bit to hopefully be more robust when errors are encountered.