EXT-7104 FIXED Removed bottom separator in the context menu over bottomtray...

EXT-7104 FIXED Removed bottom separator in the context menu over bottomtray buttons. Task implementation is already completed.

Also minor refactoring:
* updated removing of chatbar menu items
* removed useless instance members

Reviewed by Vadim Savchuk at https://codereview.productengine.com/secondlife/r/424/

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branch : product-engine