Tagging tool should set isActive on its datadef.

[#52345779]

Without this behavior, clicks on datadefs are ignored and the tagging tool doesn't work correctly. The previous solution was to explicitly add the datadef to the 'activeDatasets' key in the JSON specification of each pane that used the tagging tool, or else hope that there is only one datadef so that it's active by default.
Allow table to pick up x/y labels from datadef

[#52345779]
Fix for incorrect labels in Galileo.

[#52345779]

Zeus hand-edited gravity.js, adding 'activeDatasets' arrays to each pane specification and (incorrectly) explicitly labeling some graphs as "Position" graphs.

This commit just restores gravity.js to a compiled version of gravity.coffee.

In order for the tagging tool to work correctly, it seems the datadef must now have its 'isActive' flag set to YES. The previous commit causes the tagging tool to automatically mark its datadef as active, so that we don't need the 'activeDatadefs' that Zeus added to gravity.js. The commit before that sets the tableController to automatically use the xLabel/yLabel of a datadef if there is no explicit override in the table pane specification.