EXT-7951 RESTORED IN VIEWER-DEVELOPMENT REPO (Mini-Location panel appearance design issues)

- Added callback on show\hide Mini Location Panel event. This callback sets proper initial minimized position depending on state (shown or hidded) Mini Location Panel. Also callback shifts vertically already minimized floaters so that they don't overlap Mini Location Panel

Reviewed by Vadim Savchuk at https://codereview.productengine.com/secondlife/r/851/

--HG--
branch : product-engine