With add/insert present
Removed non-working insert and add row functionality (will need to update dynamic realm functionality). Should be a self-sufficient and releasable commit.

These functions would work if dynamic realms behaved like static ones, but at the moment there seems to be no way to circumvent to issue.
[WIP] Added back the Insert object in to array and Add object menu items.

@alazier
Fixes non-closing open file window…

…by loading the realm asynchronously, and not relying on there being a realm when the different windows awake.
Stops showing the open file dialog at startup when double clicking realm file.

@alazier @jsims @tgoyne
Merge pull request #802 from GreatApe/gk-browser-launch-issues

Gk browser launch issues