Fixed normal bug EXT-4915 (Duplicated "Buy" item in object context menu).

- Bug was caused by making "Take" menu item from object context menu consistent with the one from Build->Object menu where it was replaced by "Buy" when it was needed. But in object menu we already have "Buy" option at the bottom of the list so we don't need to hide "Take" and show "Buy" instead. Removed appearance of "Buy" instead of "Take" and made "Take" item's behaviour consistent with "Take" from object inspector gear menu.

Reviewed by Vadim Savchuk at https://codereview.productengine.com/secondlife/r/227/

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branch : product-engine