MAINT-5537 FIXED Advanced Graphics Preferences sliders are incorrect if you click Cancel rather than OK

Rename the settings that control them to be more descriptive
Remove the separate boolean setting (RenderUseImpostors) that governed both
Establish default values based on gpu class for impostors and visual muting

Remove Impostor checkbox.
That control is now merged into the right side of the impostors slider.
Maximum ARC still depends on impostors being enabled.  Once that dependency is removed
in llvoavatar then it will be necessary to reflect that change in the UI code.

Code cleanup, some per bitbucket comments.

Redo UI layout to indicate the two dependencies on the Imposters checkbox
Reverse the ARC slider

Change two sliders back to comboboxes.
Rename label "Other" to "General"
Move Max ARC to top of that list
Move Shaders block to above Mesh block

Remove a few remants used by the old hardware floater

Sky: has two dependencies; grey it out when either one is not available.
Remove Basic Shaders from Basic tab

Code improvements from bitbucket comments

Change notifications so they are emitted only when an error occurs
Put active preset at top of list
Add Maximum ARC slider
Merge two small methods into slider update code

Rename llround(..) to ll_round(..) because of a collision with MS llround (long long round) in VS2013

STORM-2082 Revert name of Reset button from Undo back to Reset.  Hopefully this will be renamed Recommended Settings.
Display a test icon (artwork needed) in the pulldown panel

Add new control variable to track which preset is active.  Save settings
to active preset when clicking on Ok button.
Initial work to make pulldown operational. Still to do: add pretty icon for current preset.
Notifications do not appear when called from this panel.

Make sure default preset is created when flyout panel is activated
Only display deleted notification upon successful deletion