EXT-5808 FIXED Added another context menu. Also Navigation Bar and...

EXT-5808 FIXED Added another context menu. Also Navigation Bar and Mini-Location bar are mutually exclusive now

- Implemented context menu for Mini-Location bar (menu_topinfobar.xml)
- Implemented function show_topinfobar_context_menu() (in llviewermenu.h) which displays context menu for Mini-Location bar.
- Functions toggle_show_navigation_panel() and toggle_show_mini_location_panel() modified so that Navigation Bar and Mini-Location bar are mutually exclusive (when the former is visible the latter is hidden and vice versa).
- Implemented method LLPanelTopInfoBar::onContextMenuItemClicked which handles \"landmark\" and \"copy\" Mini-Location bar context menu actions.

Reviewed by Vadim Savchuk at https://codereview.productengine.com/secondlife/r/607/

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branch : product-engine